Japanese Arrows

Rules

Put a number in each cell without a number so that the number and arrow in each cell indicates how many different numbers exist in the direction the cell is pointing at (not including itself).

(Rule and example from PGP IB)

History of the puzzle

Invented by Masanori Natsuhara (Japan) in 1992. First appeared on July 1992 edition of the Puzzler magazine.

Original named "何種類?" ("how many kinds").

Variants

Japanese Arrows (Complete)

Enter a digit in every cell in the grid. The arrows indicate all of the 8 directions in which the number of different digits is equal to the number in the cell. All possible arrows are given.

(Rules and example from WPC 2018 IB)

Appearances in the past WPCs

• WPC 2018/Round 5 (Japanese Arrows (Complete)) by Jiří Hrdina
• WPC 2013/Part 4
• WPC 2011/Part 5