Yuusei Rosario di Maria

Yuusei is Isaac di Maria's son and Ichirou di Maraa's father. He raised Ichirou all by himself. Just like his father, he was an exorcist and a researcher.
Yuusei was killed when Ichirou was younger.

[spoiler]
- He conducted studies on immortality
- He was object of studies himself
- He wasn't a normal child, he was a clone created by Isaac