Diehauser Belial

Diehauser Belial is the current head of the Belial Family and the Rating Game champion, ranking number one.

Appearance
Diehauser is described as a man with a graceful face who has a grey hair and grey eyes.

Personality
Diehauser is shown to be a polite man and respects his opponents and the young Devils who are rising regardless of their background, unlike most Devils who take importance in things such as pure bloods and demonic powers.

History
Not much is known about Diehauser, other than the fact he has dominated the Rating Game for a very long time, being undefeated since appearing, and is popularly known as "The Emperor" (皇帝 Kōtei) to everyone.

The Heroic Oppai Dragon
He served as Sairaorg's mentor throughout the Young Devils Gathering and was one of the spectators at Rias and Sairaorg's Rating Game, complimenting Issei and Sairaorg for their magnificent fight during the news conference after their battle.

In Volume 12, Diehauser and his peerage went to fight against the Jabberwocky created by Leonardo's Annihilation Maker but was only capable of stalling it. He later leads an alliance army from various factions to battle one of the Bandersnatch, being the first group to defeat the monsters.

The Legend of Oppai Dragon and his Lively Companions
In Volume 17, Diehauser came to visit Auros Academy while the school was about to be opened. He came to encourage the Gremory Group, the Sitri Group and the Bael Group. At the end of Volume 17, Diehauser was revealed to be a traitor to the Underworld, stating that he only wanted to fulfill the wishes of his "true king", Rizevim Livan Lucifer. He joined the Khaos Brigade to investigate an incident in Rias' territory (which previously belonged to his relative) which, according to him, involved Touji Shidou, the Heaven, and the Underworld.

Powers & Abilities
Immense Demonic Power: As the Champion of the Rating Games, Diehauser is a powerful Devil. In fact, his powers rivals that of a Satan-class Devil. Yuuto had mentioned that the top 5 champions of the Rating Games are considered to be unmovable from their positions and that they are the Ultimate-Class Devils of Ultimate-Class Devils which is further testament to Diehauser's power.

Trivia

 * In demonology, Belial is one of the Four Crown Princes of Hell and a demon in the Bible. He is said to be a mighty and a powerful king, ruling over 50 legions of demons made after Lucifer.