Samurai Sudoku ("Gattai-5") is one of the sudoku variation with overlapping sudoku grids. The puzzle consists of five grids, one in the center and the other 4 overlapping each corner grid of the central one.
5 normal 9x9 Sudoku diagrams are interweaved in a way so that no single diagram can be solved alone, but all 5 diagrams together have a unique solution.
Sudokus that no one can solve
Sudokus that no one can solve, not only including Sodukus which is very difficult but also that no one trying to solve it.