Akitsuki's childhood friend; his father owns the dojo Akitsuki once trained at. He recently transferred to Akttsuki's school and has made several attempts to reconnect with Akitsuki, all of which were rebuffed.
Suguru was supposed die in the fictional world, but was saved by Akitsuki.
Notably, Suguru is thus far the only person to refer to Akitsuki by his first name.