Nurarihyon no Mago: Sennen Makyou

Synopsis

In Rikuo's past, Rikuo's father, Rihan Nura, is seen walking with a five-year-old Rikuo and a mysterious black-haired girl. As Rikuo runs ahead, Rihan stops to observe his surroundings; suddenly, the girl stabs him from behind, killing him, while Rikuo can only look on in shock. Three years later, Rikuo is shown playing pranks on his yōkai family and learning the yōkai art of "dine-and-dash" with his grandfather, Nurarihyon. In a meeting with the leaders of the Nura Clan, to everyone's surprise, Nurarihyon declares that his grandson will be the next heir. However, Rikuo, having been told by his friends that all yōkai are evil and upon hearing of the evil deeds of the clan leaders towards humans, refuses. The following day, Rikuo misses the last bus from school and is returned home by Karasu Tengu. Once home he hears that the bus carrying his classmates has been in an accident. Rikuo transforms into his yōkai form for the first time and goes out to rescue them, leading his own Night Parade of a Hundred Demons. The accident is revealed to have been caused by some yōkai from the Nura Clan that feeds on children and whose leader expected to be named the next heir. After Rikuo kills their leader and his posse routs the other yōkai he declares that he will become the Third Heir of the Nura Clan and protect humans.

(Source: Wikipedia)