The full logical solve of the hard Shikaku for September 1 to September 7, 2026, 15 × 15. 44 steps, 4 techniques, no guessing. Step through it, or jump to any step below.
The 12 in row 1, column 11 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 12 in row 2, column 1 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 3 in row 3, column 15 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 1 in row 10, column 5 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 2 in row 9, column 2 can reach row 10, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 2 in row 11, column 3 can reach row 11, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 12 in row 5, column 4 can reach row 10, column 3, so its rectangle must cover that cell. Just one of its rectangles does.
The 6 in row 6, column 1 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 6 in row 3, column 1 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 2 in row 11, column 4 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 2 in row 4, column 4 can reach row 4, column 3, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 4 in row 4, column 6 can reach row 4, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 2 in row 7, column 2 can reach row 8, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 4 in row 8, column 1 can reach row 7, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 10 in row 8, column 7 can reach row 9, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
The 10 in row 10, column 7 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 4 in row 12, column 4 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 12 in row 13, column 4 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 2 in row 15, column 1 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 3 in row 12, column 1 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 2 in row 13, column 13 can reach row 14, column 13, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 2 in row 15, column 7 can reach row 15, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
Every rectangle the 6 in row 2, column 9 could take covers the same 2 cells. Other numbers can’t use them, and that leaves the 4 in row 3, column 11 with one rectangle.
The 5 in row 4, column 7 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 3 in row 4, column 12 can reach row 3, column 12, so its rectangle must cover that cell. Just one of its rectangles does.
Some cells can be reached by only one number. Each such number keeps only the rectangles that cover them, and after a few of these steps the 6 in row 10, column 9 has one rectangle left.
The 6 in row 11, column 8 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Some cells can be reached by only one number. Each such number keeps only the rectangles that cover them, and after a few of these steps the 10 in row 11, column 14 has one rectangle left.
Only the 4 in row 15, column 11 can reach row 15, column 13, so its rectangle must cover that cell. Just one of its rectangles does.
Try each rectangle the 2 in row 1, column 8 could still take. All but one lead to a contradiction, so it takes the one left.
Try each rectangle the 6 in row 2, column 9 could still take. All but one lead to a contradiction, so it takes the one left.
Working through which numbers reach each cell, and the cells every option of a number shares, the 4 in row 5, column 8 is left with one rectangle.
Working through which numbers reach each cell, and the cells every option of a number shares, the 6 in row 6, column 7 is left with one rectangle.
Every rectangle the 4 in row 9, column 10 could take covers the same 3 cells. Other numbers can’t use them, and that leaves the 4 in row 7, column 8 with one rectangle.
Try each rectangle the 6 in row 4, column 15 could still take. All but one lead to a contradiction, so it takes the one left.
Try each rectangle the 6 in row 6, column 11 could still take. All but one lead to a contradiction, so it takes the one left.
The 4 in row 9, column 10 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 6 in row 7, column 13 can reach row 7, column 11, so its rectangle must cover that cell. Just one of its rectangles does.
The 2 in row 9, column 11 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 8 in row 9, column 12 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 6 in row 10, column 15 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 2 in row 7, column 15 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 4 in row 11, column 10 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 6 in row 13, column 10 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.