Though outwardly brash and arrogant, Kaigaku is in fact cowardly and selfish. Like many orphans living on the streets, he grew up resorting to thievery and other immoral means to survive. He even goes so far as to sacrifice the lives of all the orphans under Gyomei's care to save his own skin. This has caused him to develop an intense form of self-preservation, often doing what in his own best interest at the expense of others.

At some point after this, Kaigaku met and became the disciple of Jigoro Kuwajima. Because of his great talent with a sword, he was poised to become the next Thunder Hashira. However, unlike other orphans who join the Corps, Kaigaku never developed a desire to slay demons or protect people. When confronted with a stronger opponent, Kaigaku quickly surrendered. Furthermore, he seems to have developed a sense of hypocritical self-righteousness. He called Zenitsu Agatsuma trash for having no pride or guts and was repulsed at the idea of succeeding Jigoro along with him. Kaigaku also seems to have a twisted perspective of 'right' and 'wrong', believing that those who judge him right (i.e., say he is worthy) are good and those who judge him wrong and have a low estimation of him are evil. Additionally, he also has an inflated ego, viewing himself as a special and gifted person.