One of Koichi's constant traits is his friendliness and overall politeness toward any stranger and acquaintance. Having a gentle heart, Koichi usually doesn't seek to harm his opponents, notably having saved Yukako from death even though she wanted to kill him before,[9] and briefly fighting Giorno Giovanna without using the strength to kill, which inadvertently saved him.[10] However, Koichi's friendliness disappears on the rare occasions he is angered, and he becomes more abrasive, violent and vulgar.