Detective Tsukauchi is an earnest, hardworking individual who has earned the right to be a close friend of All Might, enough so, that he was even entrusted with the truth about One For All and the former's true form.

As a detective working with the law, Naomasa is strict and does not approve of vigilantism, which, despite having heroic intentions, is still illegal and therefore makes them Villains. However, despite vigilantism being illegal, he is shown to be grateful for The Crawlerhelping to protect the Tokyo Sky Egg from Bomber villains.

Naomasa also cares a lot for his sister, Makoto, as shown when he desperately cried for help to All Might to rescue his sister. Makoto would often tease her brother and challenges authority (although not to the point of committing anything illegal), which would annoy Naomasa quite a bit. However, the two can get to the point of argument, such as when Makoto argued that Pop☆Step shouldn't be treated as a villain after several bombings, while Naomasa tells her to quit arguing for the sake of it.