WARNING: The following contains spoilers for Episode 11 of The Misfit of Demon King Academy, now streaming on Crunchyroll.
The Hero students of Arclanskia got the better of the demon students when they snuck holy water into the first battle between the two schools. Now Anos' group is ready to fight back.
Anos, Sasha and Ray will challenge the Hero students directly, while it's Misha Necron's job to create a castle and provide support for her fellows. She's up to the job, but danger lays ahead, and she might not see it coming.
The Ambush
Misha performs her job as expected. She conjures three demon castles within the Hero students' barriers, a truly remarkable feat, and draws back into a support role while her fellows fight the Hero students directly. As the battle outside turns in Anos' favor, Misha is walking alone deep inside one of the castles when a voice calls out to her. It's Diego, the headmaster of Arclanskia, and he's disgusted to see a demon walking around in the open. He throws open a pair of doors and uses holy magic to dispel Misha's personal barrier, injuring her in the process. He isn't done yet -- acting out of a festering, 2,000 year-old utter hatred for demons, he manifests a sword and wounds Misha even further. He's about to destroy her for good when Anos arrives and launches a counter-attack.
Anos finds it strange that the Hero students are so vicious toward the Demon King Academy students. Naturally, there is a rivalry between the human and demon realms, and of course the humans shouldn't take the demons lightly. But there is ruthless malice here that Anos can't approve of, and he believes that it all stems from Diego, who is orchestrating the entire thing and spurring his students on. In fact, Diego is using brainwashing magic to try and turn the Unitarian students against Anos, and it's time to deal with Diego once and for all.
What A Hero Really Is
Diego is arrogant, since he views himself as the embodiment of noble heroes, and he fights in the name of Kanon, the legendary Hero from days gone by. The problem is that he is a spiteful and conceited person who simply wants to torment and kill demons, and Anos certainly knows it. To that end, Anos casts a curse on Diego, the type that can manifest demonic aspects in ordinary objects or animals. But if used on a Hero, like Diego, then it will physically manifest as that person's true nature. In this case, Diego morphs into a giant and ironically demonic creature -- and Anos still isn't done.
Anos holds Diego's source in his hand, and he explains that the hero Kanon had seven of them. So long as one remained, Kanon could revive himself after death, which is what allowed him to keep coming back to challenge Anos for so long. Anos adds that Kanon would never exploit or sacrifice anyone else to achieve his goals, even if the reward was defeating Anos. This contrasts sharply with the scheming and dishonest Diego, who uses tricks and ambushes to try and take the demons down. Diego has fallen, and once Anos heals Misha, he heads off to meet Eleanor Bianca, who claims to be the very essence of magic.