What is Samurai Sudoku?

Samurai Sudoku is five overlapping 9×9 grids arranged in a cross, where each of the four corner grids shares one 3×3 box — the corner box nearest the centre — with the middle grid.

How do the overlapping grids work?

Each of the five grids follows normal Sudoku rules. The shared 3×3 boxes must satisfy both grids they belong to at the same time.

How do I solve a Samurai Sudoku?

Start with the overlapping boxes, because clues there constrain two grids at once, then work outward solving each 9×9 grid as a normal Sudoku.

Is Samurai Sudoku one big puzzle or five?

It is one connected puzzle: the overlaps tie the five grids together, so progress in one grid helps you solve its neighbours.

How many cells does a Samurai Sudoku have?

369. Five 9×9 grids would be 405 cells, but the four shared 3×3 boxes are counted once rather than twice, which removes 36.

Is Samurai Sudoku the same as 5-way Sudoku?

Yes. Samurai Sudoku is also called 5-way Sudoku or Gattai-5 — all names for the same five-grid cross layout.

Samurai Sudoku

A Samurai board: five 9×9 grids in a cross. The four shaded boxes belong to two grids at once — solve those first.

Samurai Sudoku — sometimes called 5-way Sudoku or Gattai-5 — is five overlapping 9×9 grids arranged in a cross. A true endurance challenge, and the largest puzzle on SudokuStreak.

Is it really five puzzles?

Not quite, and this is the thing worth understanding before you start. There are five grids, but they share four 3×3 boxes between them, so the puzzle has 369 cells rather than 405 — the 36 cells in the four overlaps get counted once, not twice.

More importantly, those shared boxes mean it is one puzzle. Five separate Sudokus would be five times the work and none of the interest. Here, a digit you place in an overlap has to satisfy two grids at once, which is both the main constraint and the main source of progress: solve the overlaps and the whole cross starts moving.

Expect it to take considerably longer than a single grid — not five times longer, though, because the overlaps do a lot of work for you.

Rules

Each of the five 9×9 grids follows normal Sudoku rules on its own — 1–9 in every row, column and 3×3 box.
The four corner grids each overlap the central grid by one shared 3×3 box — the corner box nearest the centre. Those nine cells belong to two grids at once and must satisfy both.

How to approach it

Start in the overlaps. The four shared 3×3 boxes are constrained by two grids at the same time, so they're usually where the first certain placements appear.
Solve the centre alongside the corners. Every digit you fix in a shared box instantly advances both the central grid and that corner grid.
Work outward. Once the overlaps are moving, treat each 9×9 as an ordinary Sudoku — but return to the shared boxes whenever you place a digit there.

Strategy

It's one connected puzzle, not five separate ones: a digit placed in an overlap counts for two grids, so those are your highest-value moves, and progress in any grid can unlock its neighbours. Samurai also carries the highest score multiplier in SudokuStreak, so a clean, hint-free solve is worth the most Sparks of any type.

Best techniques for Samurai Sudoku

These are the solving techniques that pay off most in Samurai Sudoku — each links to a full, illustrated guide.

Key Crosshatching Crosshatch each of the five grids; the overlaps get scanned twice over. → Key Naked Single The overlapping centre boxes seed singles that ripple across all five grids. → Key Hidden Single in Sudoku Scan each of the five grids independently — hidden singles rarely span the overlaps. → Key Naked Pair Applies per sub-grid; watch the shared boxes where a pair constrains two grids at once. → Key Hidden Pair in Sudoku Applies per grid; the shared boxes are a common place for one to appear. → Key Naked Triple Works per sub-grid, just as it does on a plain 9×9. → Key Pointing Pairs in Sudoku (Locked Candidates) Applies per grid, and the shared boxes are prime spots for a locked candidate. → Key Box/Line Reduction in Sudoku (Claiming) Per grid; the overlaps often confine a candidate to a single shared box. → Key Snyder Notation Keeps the pencil marks across five grids manageable. → Key Full House Common in the overlaps, where two grids fill a shared box between them. → Useful Hidden Triple in Sudoku Works per grid; rarely the quickest route on Samurai. → Useful Skyscraper Sudoku Technique Explained Works per grid on the harder Samurai puzzles. → Useful Avoidable Rectangle Each of the five subgrids is a standard uniquely-solved Sudoku where it still applies. → Key X-Wing Sudoku Technique Explained Each 9×9 grid can carry its own X-Wing; the extra size makes them more common. → Useful XY-Wing Sudoku Technique (Y-Wing) Explained Works per grid; more about juggling five boards than deep single-grid wings. → Useful Swordfish Sudoku Technique Explained Each 9×9 can host one, but you seldom need to go this deep on Samurai. → Useful Hidden Unique Rectangle Applies inside each of the five standard subgrids. → Useful Unique Loop Each of the five standard subgrids is a valid place to apply it. → Useful BUG-Lite Applies within each of the five standard subgrids. → Useful Unique Rectangle Each sub-grid is a proper puzzle, so the technique applies within each one. →

Difficulties & scoring

This type can be played on all five difficulties. The score multiplier for Samurai Sudoku is ×2 — so every point counts for more on this variant. The "normal time" below is tuned for this type.

Difficulty	Base score	Max (×2)	Normal time	Hints
easy	150	600	15 min	7
medium	300	1200	30 min	6
hard	600	2400	45 min	5
expert	1000	4000	60 min	4
evil	1500	6000	90 min	3

How the score is calculated

Your score builds up from 0 as you place correct numbers, up to the full base when the board is finished. Then two bonuses are added:

base × your progress × (1 + combo bonus + time bonus) × 2

Progress: the live score climbs from 0 to the base as the grid fills with correct numbers.
Combo bonus (up to +50%): keep a clean run for the full bonus. Each error or hint is a combo break that shrinks the bonus — but it never takes Sparks away below the base.
Time bonus (up to +50%): beat the normal time and you earn extra, proportional to how much faster you were. Finishing slower than normal costs nothing — there is no time penalty.
The total is multiplied by ×2 and never drops below 0.

Coins

The coins you earn reflect your score — the more Sparks, the more coins (about 1 coin for every 45 Sparks, minimum 1). Spend coins in the Shop on hints and Jokers.

Tip: a clean, hint-free solve under the normal time scores the highest. The Daily Challenge is always Classic and fully scored.