Overview

Toichika is a logic puzzle published by Nikoli. The task consists of a rectangular or square grid divided into regions. The goal is to place arrows in some cells according to the following rules: - Each region contains exactly one arrow. - Each two arrows are paired, they point to each other. There are no unpaired arrows. - Two regions with paired arrows must not be horizontally or vertically adjacent. - Between two paired arrows, no other arrow must be placed.