August 12 177 cm 64 kg Yakushi Clan Nura Clan

Zen is a poisonous bird youkai who specializes in making medicine; however, his species has a short life-span that causes him to become weaker as he ages. He and Rikuo were childhood friends. After being betrayed and nearly killed, he was rescued by "Night" Rikuo. Due to this, he supports Rikuo unconditionally.