He has his younger brother, Toshihiko as second-in-comand of his pack. Allthough, on the day he becomes traitorous and abusive towards his followers as well as Toshihiko, their relationship goes bad and they start having constant fights. Toshihiko wins the most which makes Saikuchi determined to take him down.
One day, a white tosa comes by and rescues Saikuchi from his brother. He instantly becomes his best friend and they both start plotting to get rid of Toshihiko and his pack which he has taken over.