当たり判定 くらい判定
The area of an object used to determine collisions.

In the [[Touhou]] games, it is represented by a small, white circle near the character's waist.

In fighting games, red ones usually represents that the move can deal hits and damage while other colors represents their hurtboxes or collision box.

h4. External links

* "Touhou Wiki: Hitbox":http://en.touhouwiki.net/wiki/Hitbox
hitbox