Masaru is a cheerful, hot-headed showoff who seems to have a more goofy outlook on life. He is extremely energetic and constantly brags about his role as the Hero and leader of the Warriors of Hope, despite only becoming "leader" by winning in Rock, Paper, Scissors (before he was "killed" and the leadership role was passed on to Monaca) - in the original JPN dub, Masaru often refers to himself using orecchi, a form of the Japanese pronoun ore, which can be rude depending on its context but is often used when a speaker wants to assert a feeling of superiority. He loves praise and fame, hinting at his more arrogant side. He is also very playful, naughty, and mischievous - he likes to boss around others due to his role as the leader and enjoys playing pranks on his fellow Warriors of Hope. However, he is always very considerate and respectful towards Monaca. He is one of the more childlike and less intelligent members of the group, enjoying very childish jokes, stomping his foot in frustration if things don't go his way, and being completely unaware of what is truly going on. He also seems to remember certain words incorrectly, like misremembering "colosseum" as "killesseum." Despite his childish and arrogant personality, he does genuinely care about the people he leads and wants them to never feel afraid anymore, so he forces himself to be brave for them. He takes his role as the "Hero" very seriously and works hard to live up to certain hero tropes, like being fearless and never losing. When talking about his goals as a Hero, he also mentions Monaca among the things that should and will belong to him, possibly out of his firm belief in the trope that the hero always gets the girl, instead of romantic interest. Though he usually appears very cheerful, he can get very upset and break down crying if he is reminded of his abusive past.

Voices for Reference (ENG): https://www.youtube.com/watch?v=wuBdobVBDNs

Voices for Reference (JPN): https://www.youtube.com/watch?v=oHt2qBmciBs&t=66s