Though they only had a brief encounter, they seem to know each other and have a stable relationship. Mitsuru encourages Jyugo to have fun and try out the new games, as he thinks he should play more while he's still young. Even though Jyugo expresses a somewhat annoyance towards Mitsuru's playful attitude, he himself admits that he's indeed a playful guy and doesn't mind the remark.
Not much is currently known about the relationship between Hajime and Mitsuru, but Mitsuru claims that the two are best friends. In turn, Hajime responds with annoyance at his antics. He often helps out Hajime to prevent the Warden from learning of Cell 13's escapes by silencing alarms.
Mitsuru is perhaps the only one that seemingly knows how the Warden acts and feels. Their relationship seems to be quite good, yet with some distinct differences in terms of how good it actually is. Mitsuru enjoys his time with the Warden as he can often be seen joking with or teasing her about her crush on Hajime when in private. Momoko on the other hand tries to act professional even if Mitsuru takes her by surprise and isn't afraid to set him straight by beating him to a pulp.