The Blood of the Koh Family is a single unaired episode of Hakyuu Houshin Engi, released in 2018 with the eighth Blu-ray/DVD volume of the series. It belongs to the story of the Houshin Plan, in which the apprentice hermit Taikoubou gathers allies to seal the evil hermits behind the oppression of the kingdom of Yin, which is ruled by the wicked hermit Dakki. The extra episode is a fantasy adventure with supernatural elements, like the series it accompanies.