Samurai Sudoku takes the logic you know and multiplies it — literally. Five standard 9×9 grids are arranged in a cross pattern, with four corner regions shared between adjacent grids. Each grid follows the same rules: every row, column, and box must contain the digits 1–9 once. But in Samurai Sudoku, the overlapping cells must satisfy two grids at once. The result is a puzzle of around 369 cells that can take 30 to 90 minutes to complete.
Samurai Sudoku: Rules, Strategies & Free Printables
The complete guide to Samurai Sudoku — how the five-grid layout works, five strategies to tackle the overlapping regions, and free printable puzzles.
Quick links: What Is Samurai Sudoku? · How Overlapping Regions Work · 5 Solving Tips · Free Printables · FAQ · All Sudoku Variants
What Is Samurai Sudoku?
Samurai Sudoku is five overlapping 9×9 grids arranged in a cross pattern (also called a Gattai-5 formation). Each of the five grids follows standard Sudoku rules: every row, column, and 3×3 box must contain the digits 1–9 exactly once. The twist is that four 3×3 corner regions are shared between adjacent grids — every cell in those overlapping zones must satisfy both grids simultaneously.
Key facts
- Also known as: Gattai-5, Butterfly Sudoku
- Total cells: ~369 (five grids × 81 cells = 405, minus four shared 3×3 boxes = 36 deduplicated cells)
- Difficulty: Hard (★★★★☆) — suitable for players who regularly complete Expert or Master difficulty standard Sudoku
- Time to complete: typically 30–90 minutes
- Rules: identical to standard Sudoku rules — only the scale changes
The overlapping structure actually helps you solve the puzzle: progress in one grid feeds clues into adjacent grids. The puzzle has five separate threads — once you pull one, the rest start to follow.
How the Overlapping Regions Work
The four corner overlap zones are where Samurai Sudoku gets interesting. Each overlap zone is a single 3×3 box shared between two adjacent grids. Every cell in that box counts toward both grids at once — it satisfies the row and column constraints of grid A and the row and column constraints of grid B.
What this means in practice
- Double constraints: A digit placed in an overlap cell eliminates that digit from the relevant row and column in both adjacent grids, not just one.
- Crossfire logic: When you know a digit must appear somewhere in a row of grid A, and the overlap limits where it can go, that forced placement also eliminates it from grid B's corresponding region.
- Solve direction: Start with the most constrained outer grid (typically whichever has the most given digits). Completing an outer grid reveals solved digits in its overlap corner, which immediately constrains the center grid.
The center grid is always the last to close because all four of its corner boxes depend on the outer grids. Finish the four outer grids first, then use the overlap digits as a head start on the center.
How to Solve Samurai Sudoku — 5 Tips
1. Solve each grid independently first
Before engaging the overlaps, work through each of the five grids using standard techniques — naked singles, hidden singles, and candidate elimination. Fill as many cells as possible in each grid independently. The more complete each grid is, the more the overlap zones tell you about adjacent grids.
2. Use overlap zones as crossfire
Overlap cells get constraints from two direction sets simultaneously: the row and column from grid A and the row and column from grid B. When you place a digit in an overlap cell, immediately note its effect in the candidate lists of both adjacent grids. A single placement can eliminate candidates across two grids at once — use this leverage.
3. Start with the outer corners
The top-left and bottom-right outer grids typically have the most given digits and close fastest. Completing an outer grid fills in its overlap corner with solved digits, which immediately seeds the center grid's corner boxes. Work outward-to-center rather than trying to tackle all five grids simultaneously.
4. Transfer digits immediately
When you place a digit in an overlap cell, annotate its effect in the adjacent grid's candidate list right away. With 369 cells, it is easy to forget that a solved digit in grid 1's bottom-right box also eliminates candidates in the center grid's top-left box. Immediate transfer prevents logic gaps.
5. Track candidates per grid
With five grids in play, mark which grid each candidate set belongs to. A small "G1", "G2" annotation next to your pencil marks saves time and prevents placing a digit in the wrong grid's logical context. This becomes especially important near the center grid, where all four overlap zones are active at once.
Free Printable Samurai Sudoku Puzzles
Samurai Sudoku printable PDFs for all difficulty levels are coming soon. In the meantime, browse our full printable collection — new formats are added regularly.
Looking for printable Sudoku puzzles?
Our printable collection covers Easy through Expert difficulty in Letter and A4 formats — free, no login required.
Browse printable Sudoku puzzlesWant daily Sudoku practice to build the skills you need for Samurai puzzles? The Sudoku a Day app offers five difficulty levels with no ads and streak tracking — building Expert-level standard skills is the best preparation for tackling Samurai Sudoku.
Frequently Asked Questions
Is Samurai Sudoku harder than regular Sudoku?
Yes, but not because the rules are harder — the rules are identical. Samurai Sudoku is harder because of scale: five grids, ~369 cells, and four overlap zones where constraints from two grids apply simultaneously. Players who regularly complete Expert or Master difficulty standard Sudoku will find Samurai Sudoku very challenging but solvable. Beginners should build standard Sudoku skills first.
How many cells does Samurai Sudoku have?
A standard Samurai Sudoku puzzle has 369 cells. Five 9×9 grids × 81 cells = 405, minus the four 3×3 overlap boxes shared between adjacent grids (4 × 9 = 36). Some publishers count 441 if they include all grid cells without deduplicating overlaps — 369 is the deduplicated answer.
What does "Gattai-5" mean?
"Gattai" is Japanese for "combination" or "fusion." Gattai-5 refers to the five-grid formation. The name is common in Japanese puzzle publications. Samurai Sudoku, Butterfly Sudoku, and Gattai-5 all refer to the same five-grid format.
Do I need to solve all five grids to complete a Samurai Sudoku?
Yes. The puzzle is not complete until all five grids are fully solved. Since the four overlap zones link adjacent grids, leaving any grid unsolved leaves its neighbor under-constrained. In practice, you typically solve the outer grids first and finish with the center grid.
Where can I find Samurai Sudoku puzzles?
Samurai Sudoku printable PDFs are coming to this page soon (free, no login required). For daily standard Sudoku practice, the Sudoku a Day app offers five difficulty levels — building Expert-level standard skills is the best preparation for tackling Samurai puzzles.
Keep Exploring
- All Sudoku Variants — Killer, Diagonal, Jigsaw, and more.
- Killer Sudoku Guide — Rules, combinations table, and strategies for the world's most popular variant.
- Arrow Sudoku Guide — How arrow sum constraints work and how to exploit them.
- Printable Sudoku Puzzles — Free printable puzzles, Easy through Expert.
- Standard Sudoku Rules — The fundamentals behind every Sudoku variant.
- Evil Sudoku — The hardest standard difficulty. Master this before tackling Samurai.