yuu turns into a demon

There were a few novels that turned into demons at the beginning that could be recommended. Among them were " Revival of Evil Spirits: The Beginning of the Fusion with a World-Destroying Demon " and " The Beginning of the Transformation into a Demon ". These novels described how the main character became a demon under certain circumstances and gained great power. They are filled with decisive killing and dark elements. They might suit your interest. I hope these recommendations will meet your needs.

One common theme is the struggle between their different natures. Since Yuu is a demon and Mika is a vampire, there's often a conflict and a need to overcome their natural instincts to be together.

My knowledge doesn't have anything related to the main character becoming a demon king. Can you provide me with more relevant information so that I can better answer your questions?

Yes, Mika does call Yuu 'Yuu-chan' in the manga.

Sure. You can start by looking on popular fanfic platforms like Archive of Our Own. There are often many works that explore the relationship between Demon Yuu and Vampire Mika. Just search for the relevant tags and you'll find a bunch of interesting stories.

I recommend The Tale of the Blood Crystal and The Ruthless Path of Magic. These novels told the story of the protagonist turning into a demon because of his family's destruction, just to take revenge. They belong to the category of fantasy novels. The plot is compact and interesting, and may meet your needs for the protagonist to become a demon of sorrow. I hope you like these recommendations!

One possibility could be that Percy, as a demon, struggles with his new identity. He might have to deal with new powers that are difficult to control. For example, he could accidentally harm his friends. He may also face discrimination from those who fear demons, even though he's still the same person deep down.

Often, Lenalee Lee is paired with Kanda Yuu in these fanfictions. She and Kanda Yuu could be involved in projects to help the survivors of the war. Their different personalities, with Kanda Yuu being more brooding and Lenalee being more empathetic, can create interesting dynamics. And there are also fanfictions where he is paired with Bookman, as they might exchange knowledge about the world post - war and how history is being rewritten.

Well, it could be that he faces a moral struggle and tries to fight against his demonic nature.

There's also Vil Schoenheit. His beauty - obsessed and perfectionist personality can interact in various ways with Female Yuu. Additionally, Idia Shroud is paired with Female Yuu in some fanfictions. His introverted and tech - savvy nature can form an interesting bond with Female Yuu as she tries to draw him out of his shell.