Reword this but without the exaggeration and emotion.
Kaiyochi's indomitable willpower is among his most defining characteristics. He is a warrior who refuses to be defeated even in the face of insurmountable odds. His unbreakable spirit is what sets him apart from the rest, giving him the courage and stamina to withstand almost any challenge that comes his way. One notable example of Kaiyochi's incredible willpower is when he sustained severe injuries from a merciless demon but refused to surrender. His determination and resilience were so intense that they left even his adversary, as well as onlookers, astonished. Kaiyochi's ability to endure and triumph in the face of adversity was considered remarkable by Yotsuyahi.