Yamada is a rock that fell off of a Yamada Construction rocks truck in Minami-ke Episode 11#Segment Three. Chiaki names it after the truck and devises an elaborate game in which she kicks it home, avoiding puddles and gutters. Just before arriving home, Kana runs in carelessly and kicks the rock into the air, sending it back onto the truck it came from, completing the circle. Chiaki chases after it but eventually falls. Her devastation is apparent during dinner that night.
Notably, Chiaki has once again personified an object by naming it after whatever happens to be in the area, a clear pattern given the other objects she has named.