Anhe Zhuan
English title: Tales Of Dark River
Japanese title: 少年歌行外传：暗河传
Type: ONA
Episodes: 12
Source: Web novel
Genres: Action, Adventure, Mystery
Studios: Passion Paint Animation
Producers: Youku
Duration: 19 min per ep
Rating: PG-13 - Teens 13 or older

Anhe, the most mysterious killer organization in the world, is composed of the three surnames Su, Xie, and Mu. Everyone was poisoned, and their lives were at stake. After learning the news, the three forces of the Anhe River took the opportunity to launch a rebellion. Su Muyu, as the leader of Spider Shadow's guard group, brought in Bai Hehuai, the genius doctor of Medicine King Valley, to heal the elders, while repelling the killers and protecting the elder Zhouquan. At this time, his friend Su Changhe in Anhe, but on behalf of the Su family joined the operation to assassinate the patriarch.

(Source: Youku, translated)