He murders his brother Riko at the end of the third book.
He knew his mother for a few years, as he is about 5 years older than Riko and their mother was killed shortly after giving birth to his brother.
Relationship with Neil Josten Edit
Ichirou and Neil have a purely business relationship. Ichirou flies out to meet Neil and assess whether he is a threat to the Moriyama family business, as he is a loose end left after the death of Neil's father, the Butcher. Ultimately, he decides to leave Neil alive, requiring Neil to tithe 80% of his earnings through Exy for the rest of his life to the Moriyama family. Through Neil, he brokers similar arrangements for Kevin and Jean, both of whom were also valuable assets.