Diabolos' appearance has not been described.
Not much is known about Diabolos' personality.
Light Novel Volume 01Edit
Diabolos was one of the four Government summoners deployed with a small group of Repliglass soldiers to hunt down Higan Meinokawa, though Azalea Magentarain considered the four to be useless for fighting Kyousuke Shiroyama. Indeed, Kyousuke defeated them all with ease. Diabolos was the second summoner he defeated. After neutralizing Perfect Game by batting away his Incense Grenade into the ocean at the start of the fight, Diabolos threw her own Incense Grenade at her feet. However, Kyousuke stole a powerful military light from one of the Pilot Soldiers and used it to blind her, causing her Incense Grenade to have no effect. Kyousuke used this brief opening to pull out and throw his own Incense Grenade into Diabolos' face, knocking her out and creating an Artificial Sacred Ground.