Despite only being 16 years old Ryouma is quite tall and muscular. Ryouma has no remorse for people who have any kind of malicious intent towards him.

Spoiler

Even before being summoned to another world was trained in various deadly martial arts and taught to have no mercy, Ryouma was capable of easily killing armored foot soldiers. In this new world, a person can absorb a portion of someone or something's strength by killing them. After coming to this new world Ryouma killed dozens of people and absorbing their strength.

(WORTENIA SENKI WIKI)