Kou is the (non-biological) younger brother of both Roku and Satoi, and a close friend of Leila. He strongly dislikes being a vampire and hates himself for being such a 'horrifying creature'. He's extremely mature and independent, but he oftentimes needs a shoulder (more specifically Leila's shoulder...) to lean on.

He enjoys learning the piano, playing video games and chewing pencils. He has a terrible habit of apologising incessantly and thus is often reminded how he does not need to apologise for small jokes taken too seriously.

Very pessimistic, his jokes range from humorous to extremely dark. When meeting people he wants to be friends with, he initially treats them coldly, but he warms up to them over time.

The most noticeable feature he has is his (ironically) hidden right eye. It's a 'clock eye'. Kou has the ability to freeze time for 5.587218237 seconds, and his eye indicates this. When he cries, the right eye's tears fall at the rhythm of the clock. you can also use it to tell the time but shh