Diodora Astaroth

Diodora Astaroth is a major antagonist in the light novel and anime series Highschool DxD, serving as the main antagonist of volume 6 and the greater scope villain of volume 1. He is the former supposed heir of the Astaroth Clan & the younger brother of Ajuka Beelzebub.

He is voiced by Makoto Furukawa in the Japanese version of the anime and Aaron Dismuke in the English version.

Appearance
He is a gentle-looking, handsome young man with blonde hair in the light novel & dark green hair in the anime. He also has a big deep scar on his chest which he injured himself to turn Asia into a heretic as part of his plan. He is usually dressed in noble clothing.

Personality
While appearing to be a gentle, well-mannered young man, Diodora is in fact a narcissistic, sinister, vile & wicked demon who will do anything to get whatever he wants. He is very obsessed with nuns & holy maidens as most of his Chess Pieces are all former nuns & holy maidens he had acquired all over the world by being the cause of their excommunication. He enjoys seeing them suffer in pain, sadness & despair as he finds it an ultimate form of entertainment. He is also incredibly childish and immature, as proven by the temper tantrum he threw upon realising he was no match for Issei.

He is also shown to be heavily disgusted with Dragons and those associated with them, as he calls Issei a "filthy dragon" but after suffering his defeat on him, he becomes fearful of him and dragons.

History
It is stated by Freed Sellzen that due to his nun fetish, he's been preying on famous nuns and Holy-maidens in various countries around the world one after the other. He would often seduce the maidens with his passionate words in order to make them fall in love with him. After the nuns and maidens were excommunicated by the church, which is devastating for them, he would later save them from the depths of their despair, and eventually rapes them physically & emotionally. Later Diodora reincarnated them into becoming his servants as they slavishly pledged their loyalty to him as a result.

Sometime prior to the series, Diodora purposely injured himself to force the kind Asia to heal him, a Devil, which resulted in Asia's accusation of her being a heretic which led to her excommunication from the Church. He was also secretly present the abandoned church at Issei's town when Raynare stole Asia's Sacred Gear, initially intending to be the one to kill Raynare and save Asia and then take her as his servant. His plan, however, did not work due to Issei defeating Raynare.

Plot
Birth of the Breast Dragon Emperor

He appeared in Volume 5 as one of the six young Devils for the Young Devil Gathering. At the end of the same volume, he reappeared in front of the Gremory group and proposed to Asia after he revealed that he was the Devil that Asia healed years ago.

In Volume 6, he was scheduled to have a Rating Game against the Gremory Team but this did not happen after he revealed that he was an ally of the Khaos Brigade. He also reveals he had Asia heal him simply to add her to his collection of nuns. Diodora then kidnaps Asia and has his peerage battle against the Gremory group. He was defeated by Issei in a one-on-one fight with Issei overpowering him out of rage at what he did to Asia. After his defeat, Shalba Beelzebub appeared. Diodora pleaded with him to help, only for Shalba to stab him with a weapon of light, and his body dissolved away.

Trivia

 * In the manga adaptation of Highschool DxD, Diodora makes a cameo as one of the guests in Rias and Riser's engagement party.
 * Diodora serves as a foil to Rias. Both are the younger sibling of a Devil King (Ajuka Beelzebub and Sirzechs Lucifer, respectively), both are the future heads of their families due to their brother's position and both have a connection to Asia. But where Rias is kind, mature and serene, Diodora is cruel, childish and psychotic. Rias cherishes Asia as a surrogate sister, while Diodora views her only as his property. Rias is greatly respected in the underworld, while Diodora is widely hated, to the point that the only reason he wasn't killed sooner was that killing him could have started a civil war.