Taizen Shiba

Taizen Shiba (大善 欺波, Taizen Shiba) is Yuuichi Katagiri's adoptive father. He is presumably deceased, and is only mentioned throughout the series as "Sensei". He is presumably killed by Yuuichi himself.

Yuuichi Katagiri
Yuuichi himself seemingly really dislikes it when people associate him with the "Shiba" name, even showing intense outbursts during those occasions.