KDP Puzzle Book Engine
✓ Verified Single-Solution Puzzles
Brand-New KDP Niche
⚠ Premium at $187 Is a Big Jump
Jikan Nazo Review 2026 — Number Mystery KDP Engine That Builds Verified Puzzle Books in One Click
◉ K. Bimal
·
September 23, 2026
·
12 min read
·
Launch Day Review
StackLens Score — Jikan Nazo
Jikan Nazo — Find-the-Number Mystery Book Engine · Ike Paz, Luke Bowes, Marina Matic
The mechanic is genuinely novel and the KDP niche is genuinely open — word search book 4,000 and sudoku book 9,000 are real problems for real publishers, and a verified number-whodunit is a real solution. Every puzzle proven to exactly one solution before export is the killer feature: no broken books means no one-star review landmines. The $19 entry is one of the lowest in the puzzle-tool space. The score isn't higher because the Premium OTO at $187 is a steep 10x jump from the FE, the front-end PDF limit (100/month) will frustrate heavy publishers who don't upgrade, and the niche — however open — is narrow enough that buyers need clear strategy to execute, not just the engine.
ℹ
This review is based on the full sales page, JV documentation, beta tester feedback, and live app screenshots. The 2 exclusive bonuses listed below are created by me and address the strategy gaps the engine itself doesn't cover.
Quick Verdict
✓ Recommended — Especially at the $19 Entry Price
Jikan Nazo occupies a KDP shelf that is genuinely empty right now. Buyers who devour whodunits and buyers who love number puzzles are both well-established Amazon audiences — and almost nobody is currently serving them both in one book. The engine that builds these books also happens to be technically impressive: every puzzle is proven to exactly one solution before it prints, which is a harder problem to solve than it sounds and the reason this shelf has been empty. At $19 the risk-to-try is minimal. The honest caveats are the steep Premium OTO, the FE PDF limit, and the fact that execution — niche selection, listing strategy, series building — is entirely on you. Buy at FE plus Pro ($76 combined). Think carefully before committing to Premium ($187) until you have your first book ranked.
What Is Jikan Nazo?
Jikan Nazo is a Find-the-Number mystery puzzle book engine that builds complete elimination-puzzle books for Amazon KDP paperbacks and printable marketplaces. Built by Ike Paz and Luke Bowes of Royalty Prints, with the core verification engine created by Marina Matic.
The mechanic: every book contains a register of numbers — hundreds or thousands of them — and a set of clues. One number is the answer. The clues eliminate every other number one by one, through pure logic, until exactly one survives. The solver's job is to find it. It is a number whodunit.
What makes it technically significant: every puzzle is proven to exactly one solution before the book exports. Every clue must be true of the answer. Every clue must eliminate at least one entry. Remove any single clue and the case must re-open — meaning no clue is filler. This verification problem is what kept this shelf empty for years. Other puzzle generators produce books with two answers, or broken clue chains, or guesswork puzzles dressed up as logic. Jikan Nazo produces books you can stand behind.
42,000
Max Register Entries
$155
Max Per Stacked Buyer
The Elimination Mechanic — Why It Works When Everything Else Is Saturated
The word search and sudoku shelves on Amazon are not just competitive — they are genuinely saturated. Thousands of near-identical books, identical covers, identical "proven" formats, all fighting for the same category rankings. New publishers who follow the standard KDP advice and publish into those categories arrive years late to a shelf already full.
The elimination number-mystery format is different in a structural way: it requires the solver to engage in actual logic, not pattern recognition. You don't scan for words. You don't trial-and-error numbers into a grid. You read a clue, cross off every number that clue eliminates, and watch the register shrink until one number stands alone. The answer is proven by the clues, not discovered by chance.
Buyers who want that experience — the whodunit reader who also loves numbers — have almost no books to choose from on Amazon today. That gap is the opportunity Jikan Nazo is built to fill.
🔢
The Register
Hundreds or thousands of numbers on the page. One is guilty. The rest are innocent until eliminated.
→
🔎
The Clues
Each clue eliminates a slice of numbers. Pure logic — no guessing. Every clue true, every clue necessary.
→
✅
The Survivor
Exactly one number survives all the clues. Proven before export. The answer key names every eliminated entry.
How It Works — 3 Steps to a Published Book
01
Create
Choose your difficulty (Gentle, Standard, or Fiendish), your register size (up to 42,000 entries), and your KDP trim size. Click generate. The engine builds and verifies the whole book in one run — register pages, clues, front matter, rules page, coded answer, and the answer key with per-clue elimination witnesses. Guided setup walks you through your first book.
02
Export
Every KDP trim size is handled — margins, gutter, bleed, mirrored margins, large print at 18pt, page numbers, chapter title banks. A pre-flight check tests the book against KDP's own print specifications before you upload, so nothing bounces at submission. Export to PDF for KDP or PNG for printable marketplaces. The same book runs on both income rails.
03
Collect
Upload to Amazon KDP as a paperback — Amazon prints, ships, and pays. The same export sells as a printable PDF on Etsy or similar platforms. Press the button again: every book is a fresh verified case. Same seed, same book — any book can be rebuilt exactly if you need to reformat or update it later.
Real Member Income Proof
The income dashboards on the sales page are from members of Royalty Prints' existing tool family — the same ecosystem Jikan Nazo enters. These are real KDP royalty dashboards and real WarriorPlus sales reports, not mock-ups. Individual results vary, but these are the people your buyers are joining:
$14,395
642 orders · 5.9% conversion
From the Royalty Prints member group — puzzle books via KDP
€1,304
Approximated KDP royalties
European market — same books, different marketplace
#6
Amazon Scrabble Books ranking
Beta tester — organic sales within days of publishing
27
Sales in first month
"WARNING this is addictive" — member who published 2 new series
The beta tester quote that matters most: "I made a few books. Found no bugs in the quiz logic. There was only one answer!" — This confirms the core technical claim independently. The verification engine works.
Core Features
🧩 Verified Elimination Engine
Every puzzle proven to exactly one solution before export. Every clue true, every clue necessary. Remove any clue and the case re-opens. No guessing, no broken books, no angry reviews.
⚡ Whole Books in One Run
Up to 42,000 entries generated, clued, and verified in a single click. Three difficulties: Gentle, Standard, Fiendish. Batch generation for building series without repetition.
📄 Full KDP Page Setup
Every KDP trim size, margins, gutter, bleed, mirrored margins, large print at 18pt, page numbers, chapter title banks, and a pre-flight check against KDP's print requirements.
📚 Front & Back Matter Included
This-Book-Belongs-To page, copyright, rules pages, coded answer page, reveal page, and answer key with per-clue elimination witnesses. A complete book, not a stack of puzzles.
🔑 Seeded Generation
Same seed, same book every time. Change the trim size or font and the book rebuilds exactly — puzzle untouched, layout adjusted. Book and asset library for your entire catalog.
📦 Flexible Exports
Unlimited PNG plus 100 print-ready PDFs/month on FE. KDP paperbacks and Etsy printables from the same click. Two income rails, one build.
🎨 Custom Imports
Import your own number list and chapter titles. Birthday books, anniversary books, themed specials — personalised books from your own data.
📖 Guided Setup
Step-by-step guided setup walks through the first book from scratch. No puzzle design experience, no KDP experience, and no technical background required.
Pricing & Funnel — Honest OTO Breakdown
| Offer | Price | What It Adds | Verdict |
|---|
| Front-End — Jikan Nazo | $19 | Find-the-Number engine, 28,500 register, 100 PDFs/month, PNG unlimited, all 3 difficulties | Buy This |
| Pro — 9 More Registers | $57 | Phone numbers, timestamps, lottery tickets, IP addresses, card hands + more. 7 languages, unlimited PDF/DOCX/PPTX | Recommended |
| Premium — Story Registers | $187 | 10 story registers (dates, coordinates, coded names, colours, addresses), The Casebook (printed story pages), SVG export | After first book ranks |
| Icon Nazo — Second Engine | $47 | Icon-based mystery puzzle books — same one-click verified build, kid-friendly angles, every export format | Optional |
On Premium at $187: The story registers and Casebook features are genuinely powerful — they take the book from "number puzzle" to "narrative number mystery" which is a stronger product. But $187 is a 10x jump from the $19 FE and you should not commit to it before you have at least one standard book live and selling. Validate the niche first, then upgrade to Premium for the narrative layer.
⚠ Honest Flags
⚠️Flag 1 — 100 PDF/Month Limit on the FE
The front-end caps at 100 print-ready PDFs per month. For a publisher building one book at a time this is plenty. For anyone building a serious series catalog or running multiple titles simultaneously, this limit will frustrate quickly. Unlimited PDF export is Pro-only ($57). Factor this into your budget at purchase — buying FE now and upgrading to Pro later costs the same as buying both upfront, but means an extra checkout step.
⚠️Flag 2 — Premium at $187 Is a Steep Jump
FE at $19 to Premium at $187 is almost 10x. The Casebook feature (printed story pages around each puzzle) and story registers (coordinates, coded names, card hands) are the Premium differentiators — and they're genuinely compelling for higher-end mystery book production. But the right time to buy Premium is after you've validated that your standard books sell, not at the initial checkout. Don't upgrade to Premium under launch-window pressure unless you have a clear use for those specific registers.
⚠️Flag 3 — The Niche Is Open But Narrow
Number mystery puzzle books are not yet a broad category — they're a fresh niche that needs to be built rather than entered. Buyers exist (whodunit readers and number puzzle fans both), but they're not currently searching "elimination number mystery book" because the format barely exists yet. Your success depends on understanding how to position within existing categories (logic puzzles, brain teasers, mystery books) until the format builds its own search volume. This is actually an advantage — early publishers own the category — but it requires active listing strategy, not passive reliance on organic search.
Pros and Cons
✅ WHAT WORKS WELL
Every puzzle verified to exactly one solution — no broken books, no one-star review landmines
Genuinely new KDP mechanic — almost no direct competitors on Amazon today
$19 entry price is among the lowest in the KDP tool space
Pre-flight KDP check prevents upload rejections before they happen
Two income rails — same PDF exports to KDP paperback and Etsy printable
Large print built in at 18pt — senior market captured from the same build
Custom number import enables personalised and gift books
Seeded generation means any book can be rebuilt exactly later
Real beta tester confirmation of puzzle logic — independently verified
Ike Paz and Luke Bowes have a documented WarriorPlus track record
❌ HONEST CAVEATS
100 PDF/month limit on FE — heavy publishers need Pro
Premium at $187 is a steep jump from the $19 FE — buy only after first book validates
Niche is open but narrow — requires active listing strategy, not passive SEO
No guarantee of sales — success depends on execution, niche choice, and listing quality
Icon Nazo ($47) is a separate engine — not a bonus, an additional purchase
Who Should Buy Jikan Nazo
KDP publishers already making sales who want a genuinely fresh mechanic to add to their catalog without switching platforms or learning new processes
New KDP publishers who have tried crowded categories (word search, sudoku) without results and want to enter an empty shelf from the beginning
Printable sellers on Etsy who want a new product type — the PDF export works directly on Etsy as a digital download
Logic and puzzle enthusiasts who have domain knowledge in the whodunit/mystery space and want to build a catalog around a format they understand
Series builders who see the difficulty-ladder opportunity (Gentle → Standard → Fiendish) and want to build a recurring royalty catalog systematically
People expecting passive income without execution — the engine builds verified books, not rankings. Listings, categories, and series strategy are still your job
Buyers without budget for Pro who will hit the 100 PDF/month limit quickly and find the FE frustrating without upgrading
Six Book Types You Can Build Tonight
🔢
Classic Number Hunt Series
Flagship format · Gentle to Fiendish difficulty ladder · 5-book series
👓
Large Print Senior Edition
18pt built in · Senior market · Gift buyers for parents
🎓
Kids & Classroom Logic
Gentle difficulty · Educational positioning · Etsy printable packs
🎁
Personalised Gift Books
Import your own numbers · Birthday / anniversary · $14.99+ price point
✈️
Travel & Commute Puzzles
Small trim · One-page mysteries · Airport/train impulse buy
🎄
Seasonal & Holiday Editions
Themed chapter titles · Annual recurring sales · Christmas, Halloween, Valentine's
My 5 Exclusive Bonuses — $345 Total Value
Purchase Jikan Nazo through my link, forward your WarriorPlus receipt to kbimal@thestacklens.com with subject "Jikan Nazo Bonus Claim" and receive both bonuses within 24 hours. Both are browser-based tools — no download required.
$345 in Exclusive Bonuses
5 strategy tools built to fill the gaps the engine doesn't cover
FormatBrowser App — 3 interactive tabs — no download required
What it isThe strategy layer the engine doesn't provide. 10 profitable niche profiles (Classic Number Hunt, Senior Large Print, Kids/Classroom, Gift/Personalised, Travel, Fiendish Collector, Seasonal Holiday, Cozy Mystery Crossover, Mindfulness, Etsy Printables) — each with full brief: the angle, which difficulty to use, Amazon category paths, chapter theme ideas, and series tip. Plus 4 proven series blueprints (Difficulty Ladder 5 books, Seasonal Rotation 4/year, Niche Crossover 3 books, Gift Series 12 books) and an 8-point competition checklist to run on Amazon and Etsy before building a single book.
Why you need itJikan Nazo tells you how to build the book. This tool tells you which book to build, which category to target, and how to check that the category is worth entering before you commit time to it. The engine without a strategy is a solution looking for a problem.
FormatBrowser App — 4 interactive tabs — no download required
What it isEverything between Export and your first royalty. Tab 1: Title Builder with 5 proven KDP title formulas (Difficulty Series, Niche Audience, Gift/Occasion, Classic KDP, Large Print) — fill in your specifics and get a ready-to-paste title with live character count and pass/warn/fail check. Tab 2: 8 Amazon category paths with full breadcrumbs, badge-coded by priority, plus the email template for requesting a 3rd and 4th category from KDP support. Tab 3: Etsy Listing Generator — fill in 5 fields, get a complete Etsy listing (title, 12 tags, full description) copy-paste ready. Tab 4: Pricing guide for KDP paperback (6 format tiers) and Etsy printable (bundle strategy) with royalty math included.
Why you need itA verified book in an empty niche still needs a discoverable listing. Most first-time KDP publishers underprice, pick the wrong categories, and write titles that don't match buyer search intent. This tool removes all three mistakes before you publish.
FormatBrowser App — 4 interactive tabs — no download required
What it isFill in your book details → get a complete cover brief with color palette (6 mood presets: Noir, Cozy, Holiday, Minimal, Classic, Adventure), typography direction, imagery concept, Canva search terms, and back cover copy — all copyable. Includes a cover design guide for KDP puzzle books, a spine formatter with width calculator and print eligibility check, and 4 back cover copy templates for different audiences.
Why you need itThe engine creates the interior. This tool creates the cover brief that produces a cover that sells. At Amazon thumbnail size (160px wide), buyers decide whether to click in under a second. A cover brief built for that constraint is what separates a book that converts from one that doesn't.
FormatBrowser App — 4 interactive tabs — all calculations run live in the browser
What it isTab 1: Single Book Royalty Calculator using KDP's exact formula across 5 marketplaces (US, UK, DE, CA, AU) — input your trim, pages, interior type, and price, get your real royalty per sale and monthly income projection. Tab 2: Series Revenue Projector — model a complete book series with individual prices and sales estimates, see total monthly and annual royalties. Tab 3: Etsy Net Revenue Calculator with full Etsy fee breakdown. Tab 4: Price Optimization Table — every price from $7.99 to $19.99 with the best-royalty row highlighted.
Why you need itMost new KDP publishers underprice. At $12.99 vs $9.99 on a 150-page 6×9 book, the royalty difference is over $2 per sale. The optimization table shows exactly where you're leaving money on the table — and what a 5-book series actually projects in real income before you commit to building it.
FormatInteractive Browser Checklist — progress saves automatically to your browser · 5 phases · 30 items
What it is30 checkable items across 5 phases: Pre-Launch (7 items — verify export, margins, cover specs, keywords, categories before uploading), Week 1 — Publish & Setup (8 items — KDP upload, Etsy listing, Author Central, extra categories request, KDP ads optional), Week 2 — Traffic (7 items — Facebook groups, Pinterest, Etsy featured listing, Look Inside activation), Week 3 — Reviews (5 items — KDP review request button, author copies, review page for Vol. 2), Week 4 — Series (3 items — build Vol. 2, analyse dashboard, plan 90-day calendar). Progress bar tracks completion across all 30 items.
Why you need itAmazon's ranking algorithm weights the first 14 days after publish disproportionately. A sale in week 1 has more ranking impact than the same sale in month 3. This checklist is sequenced to get every traffic source live before the critical window closes — so your book enters its algorithm window with momentum, not silence.
Score Breakdown
9.0
Niche Novelty
The KDP elimination number-mystery shelf is genuinely empty. Word search #4,000 is a real problem. This is a real solution.
8.8
Puzzle Verification
Every book proven to one solution. Per-clue elimination witnesses in the answer key. Beta testers confirmed zero logic bugs. This is technically hard to build and they built it.
8.5
FE Value at $19
$19 for a verified book engine with 3 difficulty tiers, all KDP trims, pre-flight check, and 100 PDF exports is genuinely strong value for the price.
8.0
Ease of Use
Guided setup, one-click generation, and live page previews make the technical side accessible. The strategy side (niche, listing, series) is not covered by the engine.
8.2
Income Potential
Two income rails (KDP + Etsy), recurring royalties, difficulty-ladder series architecture, and an empty shelf to build into. Strong potential — execution-dependent.
7.5
Funnel Pricing
$19 FE is excellent. Pro at $57 is fair. Premium at $187 is a steep jump that should come after the first book validates, not at initial checkout.
8.3
Overall StackLens Score — Recommended
Final Verdict
TheStackLens Final Verdict
Jikan Nazo — 8.3 / 10 — Recommended at FE + Pro
Jikan Nazo earns its score on the strength of three things: a genuinely open KDP shelf, a technically impressive verification engine that solves a real problem, and a $19 entry price that makes the risk-to-try minimal. The beta tester who confirmed zero logic bugs and "there was only one answer" is more valuable than any sales page screenshot — independent confirmation of the core technical claim is exactly what this kind of tool needs and rarely gets.
The caveats are real but not dealbreakers. The 100 PDF/month FE limit and the $187 Premium jump are the two numbers to plan around before you buy. Neither prevents you from building and publishing books — they just define where the tool's ceiling sits at each price point.
Buy the FE ($19) and Pro ($57) together — $76 total. Build your first two or three books. Get one ranked and see the first royalties. Then decide whether Premium's story registers are worth $187 to you based on real results, not launch-window pressure.
Frequently Asked Questions
Do I need any writing or puzzle design experience?+
None. The engine generates the register, the clues, the front matter, the answer key, and all the back matter. You pick settings (difficulty, register size, trim) and press one button. Guided setup walks you through your first book from scratch. If you can use a website form, you can use Jikan Nazo.
Are the puzzles really solvable by just one answer?+
Yes — this is the core technical claim and it's been independently confirmed by beta testers. Every book is proven before export: every clue is true of the answer, every clue eliminates at least one entry, and removing any single clue would re-open the case. The answer key names, for every clue, an entry that only that clue eliminates — so you can verify the logic without solving the whole puzzle. Multiple beta testers tested the engine from every angle and confirmed no logic bugs.
What is the difference between Gentle, Standard, and Fiendish?+
Gentle books use fewer clues and each clue eliminates more entries — the register shrinks quickly and the solution appears faster. Fiendish books use more clues and each clue eliminates fewer entries — the register shrinks slowly and the last few numbers fight back. Standard sits between the two. All three are built and verified by the same engine; difficulty is a configuration setting, not a different product.
Is the 100 PDF/month limit on the FE a real constraint?+
For a publisher building one book at a time, 100 PDFs per month is more than enough — each book typically needs one or two export versions. For anyone building a series catalog of 10+ books simultaneously, or running multiple trim-size variations per title, this limit will become a constraint within the first month. Unlimited PDF (plus DOCX and PPTX) is in the Pro upgrade at $57. If you plan to publish seriously, budget for Pro at purchase.
Can I sell these books on Etsy as well as Amazon KDP?+
Yes. The same PDF the engine exports for KDP sells on Etsy as a digital printable download. One build session produces both income streams. Etsy printable puzzle PDFs are a growing market with significantly less competition than Amazon for this format. The Etsy Listing Generator in my bonus toolkit (Bonus #2) creates a complete Etsy listing — title, tags, and description — from five inputs.
What is Icon Nazo and is it worth buying?+
Icon Nazo is a separate engine — not a Jikan Nazo feature — that builds icon-based mystery puzzle books using the same one-click verified build system. Instead of numbers, the register contains icons, making it suitable for kids' books and gift formats with visual rather than numerical content. At $47 it's an optional fourth purchase. Recommendation: buy FE and Pro first. If Jikan Nazo books are selling, add Icon Nazo to expand your catalog into the kids' and gift markets.
How do I claim the 5 exclusive bonuses?+
Purchase Jikan Nazo through my link on this page, then forward your WarriorPlus purchase receipt to kbimal@thestacklens.com with subject "Jikan Nazo Bonus Claim" and include your order number. Both bonuses will be delivered within 24 hours. They are browser-based tools that open directly in any modern browser on desktop or mobile — no download or installation required.
