Yuuichirou Kurono

According to Victor Licht, Kurono is known as "The Maddest" in contrast to Benimaru's status as "The Strongest". Kurono is a very stern, confident and powerful individual. Despite that he is fixated on the weakness of others and this obsession defines much of his personality. He claims his ideal world would protect the strong and crush the weak. It is implied to be a means of measuring his own strength without the risk of being hurt. Scientists working with him in the Development Lab believe that Kurono's love of destruction and violence was what caused him to destory his right arm.

(Source: Fire Force Wiki)