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 (TV Mini Series 2010) - IMDb

Nerdilista Neda: Anime Review Sunday: Demon King Daimao

Junko Hattori from Demon King Daimao

Demon King Daimao / Characters - TV Tropes

Akuto Sai, Demon King Daimao Wiki

Ichiban Ushiro no Daimaou – 08 – Random Curiosity

Demon King Daimao / Characters - TV Tropes

Demon King Daimao/Characters - All The Tropes

Ichiban Ushiro no Daimaou episode twelve (final)

Boichiro Yamato VS Battles+BreezeWiki