Donten ni Warau Gaiden: Ketsubetsu, Yamainu no Chikai 7.40

Other Name: Donten: Laughing Under the Clouds - Gaiden: Chapter 1 - One Year After the Battle, Cloudy Laugh Gaiden, Laughing Under the Clouds Gaiden, 曇天に笑う＜外伝＞ ～決別、犲の誓い～

Summary: 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.