Yokoo and Satou/Synopsis

Story
Satou and Yokoo are minor characters in the series, being shown as Kou's friends. They appear to have been friends for a long time, having been sorted in the same class as Kou and Mitsuba in their first year.

Mitsuba Arc
Yokoo and Satou are shown to have known Mitsuba when he was alive, and Yokoo recognized Mitsuba's camera, reminding Kou of who he was.

The Three Clock Keepers Arc & Mokke of the Dead
Whenever a supernatural runs loose in Kamome Academy, Yokoo and Satou are almost always one of the victims. This is shown when Mirai turned them both into easy going old men and the Zombie Mokke turned them into candy zombies.

Esoragoto Arc
In Mei Shijima's painting world, Yokoo and Satou are very similar to in the real world, the only noticeable difference being that they are friends with Mitsuba. They go to school, bake cookies, clean the pool, and generally hang around him and Kou.