At first glance - he's a weak guy. Arutsu is one prone to sickness and has always been. He literally fights bacteria and viruses in other people, with his friends. Our weak hero appears! Wait… maybe he's not so "weak" when he fights?! [Wikipedia](https://ja.wikipedia.org/wiki/%E3%83%80%E3%83%96%E3%83%AB%E3%82%B2%E3%83%BC%E3%82%B8)