Shinji was a member of The Yakuza clan and the assassin organization Tech Ninjas. He had a plan to take over the Yakuza by making a coup but when clan's tattoo artist Holly Togram found out about the plot, her death became his first concern. He tried to get her killed by the Tech Ninjas but their efforts were countered by Takeshi Kovacs—under the alias of Ken—and Gena, a CTAC detective.
After sending ninjas to kill Holly and they failed, Shinji met Takeshi, Holly and Gena at the Wild Geese. Holly revealed Takeshi and Gena to be her bodyguards and that she was attacked again. Hearing that and as one of his men showing disrespect towards Takashi, Shinji cut one of his subordinate fingers and offered it to Takeshi, but Takeshi refused to take it. Shinji then told Ogai to prepare their most expensive room for Takeshi and Gena.
Later Holly proceed inking Shinji's tattoo preparing him for succession, while Genzo and Takeshi were speaking. Genzo explained the syndicate code and how after succession, the previous boss dies along with its stack.
Shinji was angry that the ninjas failed to kill the girl and send out another group. He wanted Holly dead, as without her, no one could access the tattoo program and he won't experience a real death, thus will remain boss forever.
On the day of the succession, an explosion occurred, which Shinji was as last opportunity and send out the ninjas to kill the bodyguards. Genzo then came to him, telling him they can't let people intervene with the succession and they will complete the tattoo earlier and from behind Holly drugged Shinji, knocking him out.
Holly then deleted Shinji's stack and transferred Genzo's stack inside him. It was revealed that the Founder of Mizumoto syndicate was doing this during each succession and instead of giving his position and life, he was taking over the bodies of the new bosses.