Poison Wings Flutter in the Bamboo Thicket

S1 E2: Zen, the master of potions who has always been like a brother to Rikuo, pays a visit to the Nura Clan, accompanied by his servant Hebidayu. Nurarihyon had invited Zen, seeking his help to convince Rikuo to become the Third Heir. But a chat with Zen doesn't help change Rikuo's mind at all, and Zen loses his temper with him. His rage, however, causes him to collapse because his poisonous wings have gradually made him weaker.