Kojiro Kaoru is a calm intellectual, well-known even outside of "S" as a famous and successful AI calligrapher. He's been shown to treat clients and strangers with polite respect,[5] but is often prickly towards those closest to him, most prominently his fellow "S" member and childhood friend Kojiro Nanjo. Kaoru often loses composure when dealing with Kojiro, perhaps due to their contrasting personalities, and the two usually end up bickering and calling each other names whenever they disagree