Kaoru Sakurayashiki

Kaoru is 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, but is often prickly towards those closest to him, most prominently his fellow "S" member and childhood friend Kojiro Nanjo.
Kaoru is also notably competitive when skateboarding - but does truly trust and care for those who he considers his friends.