Yuka Katagiri

Yuka Katagiri (片切 友華, Katagiri Yuka) is Yuuichi Katagiri's adoptive mother who is presumably deceased and is only mentioned throughout the series.

History
Sometime while appearing to be bedridden in a hospital, she taught Yuuichi that friends are "more important than money".

Yuuichi Katagiri
In contrast to Taizen, he has a good opinion of her. According to him, she taught him kindness and how valuable humans are.

Etymology

 * The name Yuka means "friend, companion, pal" (友) (yu) and "flower, petal" (華) (ka).
 * Yuka's surname Katagiri means "one-sided cutting" (片切).