Brief:
Put your ninja logic to the test with this shuriken-themed Sudoku. You’ll need patience, observation and a sharp mind to complete the grid.

Situation:
Your training has brought you to the dojo’s secret puzzle chamber. Before you can progress to the next stage of your mission, you must prove that you can recognise patterns and maintain perfect focus. Four different shuriken symbols have been placed throughout the grid—but some spaces are empty.

Can you restore the pattern before your training master returns?

Rules:

• The puzzle is a 4 × 4 grid divided into four 2 × 2 boxes.
• Fill every empty cell with one of the four different shuriken symbols.
• Each row must contain all four different shuriken symbols.
• Each column must contain all four different shuriken symbols.
• Each 2 × 2 box must also contain all four different shuriken symbols.
• A shuriken symbol can appear only once in each row, column and 2 × 2 box.
• Use the symbols already provided as clues to work out where the missing shuriken belong.

Shinobi Challenge:
No guessing. A true shinobi observes, thinks and strikes only when the path is clear. Can you complete the Sudoku using pure deduction?