Peterhausen, Ichiban Ushiro no Daimaou Wiki

Peterhausen first appeared in the series on episode 5 trying to kill Etou. Later in the episode, Sai defeated Peterhausen while saving Etou making Sai Peterhausen's master. Peterhausen is a dragon formed by the first demon king. He died in a war with his master. the current demon king in the series, Akuto Sai. Before Peterhausen died, he bit off his tooth as a remembrance gift.

Demon King Daimao / Characters - TV Tropes

Ichiban Ushiro no Daimaou (Demon King Daimaou)

Crunchyroll - Ichiban Ushiro no Daimao - Overview, Reviews, Cast, and List of Episodes - Crunchyroll

Sai Akuto, Ichiban Ushiro no Daimaou Wiki

My Anime Land - Title: Ichiban Ushiro no Daimaou Other name: Demon King Daimao; Ichiban Ushiro no Dai Maō; いちばんうしろの大魔王 Genres: Action, Comedy, Ecchi, Fantasy, Harem, Magic, School #12 Ep #6 Special

Akuto Sai, Demon King Daimao Wiki

Demon King Daimao / Characters - TV Tropes

Akuto Sai, Demon King Daimao Wiki

Demon King Daimao Episode 12 Review - Best In Show - Crow's World of Anime