Osuki is a Rumelian warrior with a hot temper and a strong desire to protect his people by any means necessary, including force. Having watched the Rumelians persecuted and exiled by the Deskunte, he is deeply resistant to the idea of coexistence and pushes aggressively for the Simurians to take what they need from Earth. His willingness to force confrontation — particularly his unauthorized entry into Tokyo and interference with the Great Purification Ritual, which he believed was killing Kalyans — is directly responsible for escalating the human-Simurian crisis. He is later casually knocked out with a single Black Flash from Yuji Itadori when he attempts to attack him.