it was a lame reason and sayuri even calls him a loser for it. it sounds like a fanfiction for how lame it was. he had a girl he liked who was a delinquent. she stopped doing crime after getting married. he found her again and if i recall, thought that she shined the most when committing crime. wanted to set up a criminal japan so that he can be noticed by her again/have her think he was cool or something.