Donten ni Warau Gaiden: Ketsubetsu, Yamainu no Chikai
English name: Donten: Laughing Under the Clouds - Gaiden: Chapter 1 - One Year After the Battle
Genres: Action, Supernatural
Type: Movie, Episodes: 1
Aired: Dec 2, 2017
Studio: Wit Studio
Source: Manga
Rating: PG-13 - Teens 13 or older
Synopsis:
One year has passed after the great battle against the "Orochi" (gigantic snake). Tenka had been paralyzed from the final battle and he took part of the government's human experiment before the battle. Tenka withdrew himself from society, but his younger brothers, Soramaru and Chuutaro, find out the secret past about their older brother.

(Source: Amazon Prime Video)