At first glance, Shinjiro is abrasive, cold, and uncaring of the world around him. He tends to meet most questions with crass cynicism and finite statements designed to end a conversations succinctly and without the possibility of continuing. He tends to avoid unnecessary conversations of all kinds, and doesn’t have a high tolerance for anything he decides is bullshit. He isn’t afraid of sharing information if the situation calls for it, though, and keeps his ear to the ground most of the time so he tends to have more of a handle on situations than his teammates. He’s quiet most of the time, which gives him the time to listen rather than speak. He just knows things that are discussed around him, and he tends to get around, so he hears a lot of things.
Beneath that hardened shell, however, is a gentler person, capable of caring deeply for those around him, particularly those he feels he needs to protect. While still a loner, and very stubborn and set in his ways, he isn’t against changing if he feels the cause is worth fighting for or he feels responsible for the situation. After the death of Ken’s mother at his hand, Shinji separated from SEES for two years, feeling his power was meaningless and only got those around him hurt. It wasn’t until Ken Amada joined the team that Shinjiro returned to protect the boy he’d orphaned.
Contrary to his outward appearance and demeanor, Shinjiro is a very clean and well-balanced person, concerned about how his teammates are taking care of themselves and how they’re eating. He has a particular fondness for Akihiko, his childhood friend of fourteen years, and Mitsuru whom he met in middle school when he and Akihiko joined SEES and the only other members at the time. The only other member of the team Shinji shows any sort of affection for is Koromaru, a dog of particular courage and determination. Shinji makes Koro-chan food from time to time, which he doesn’t actually for the rest of the team.
To most people, Shinjiro comes off as frightening, intimidating, and not someone they should cross, and he likes it to stay that way. He keeps his softer side hidden completely from everyone, though it does shine through to some of the more perceptive members of SEES from time to time. He’s very straightforward, both in how he deals with people and how he handles combat. He’s stubborn and determined, and never strays from his chosen course of action. Once Shinji has set his mind to something, that’s what he’s going to do, like it or not, and you better not have any objections to it, or else.
While Shinji has a deep concern for all his teammates and their wellbeing, he has a distinct concern for himself. He doesn’t take his appearance into account at all, and even goes so far as to shrug off healing or support when wounded in battle. His fate was sealed when he killed an innocent bystander, as far as he’s concerned, so his life is pointless. If he can protect those around him, then that’s enough. It’ll never erase the past, it’ll never bring Ken’s mother back or erase the boy’s scars from seeing his mother murdered before his eyes, but if Shinji can protect him, then at least his power was good for something. Even before Ken’s mother, when he first joined SEES, he only joined because Akihiko had. He’d always felt protective of Akihiko, and it was his place to stay at Aki’s side, no matter what.