Toaru Majutsu no Index - Volume 6, Chapter 4: Stop Sign. Beast_Body,_Human_Heart.

Shu Yu transmigrated and became the original novel’s violent and brutal female Demon that caused the supporting male character, AKA hidden Boss, to become batsh*t crazy. However, right now, the Boss is just a lowly slave that was just given to her. What should she do?

- Description from Novelupdates

You Liangxing would never open the speech function in game.
That was because his voice was…
Particularly! Kittenish!

But there was one day, he queued up with a teammate who had so much to say that they may as well explode. Vexed to the point of no return, he contributed a voice that was capable of splitting heaven and earth, “Don’t BB.”
The other party who was being scolded stilled. In the ensuing silence, he suddenly let out a long, relishing… Moan.
You Liangxing: “…..”

Later —
He realised that the person was a great god,
Much later,
Without him realising,
He became the great god’s royal healer.
…. And also his boyfriend.

- Description from Novelupdates

I possessed a minor character who marries the prince. I’m not thrilled about it. The prince is a scumbag who flirts with the heroine despite being engaged and eventually gets defeated by the original male lead. In the epilogue, all he does is apologize to his fiancée and marry her, with barely a line to his name. Well, his personality is twisted, but at least he’s handsome. And since he’s the third prince, he doesn’t have to shoulder the burden of ruling the kingdom. That’s decent husband material, I suppose. Go ahead, make a fool of yourself. You’re going to marry me anyway. I’ll just sit back and enjoy watching your embarrassing history unfold. “Doris Redfield. Don’t expect me to ask you to dance at this ball. Maybe not at the next one either. Or the one after that.” “Yes, Your Highness. As you wish.” “Even though we’re engaged… wait, what?” “It’s just a joke proposal our parents once tossed around, isn’t it? You don’t need to take it seriously, Your Highness. I’m really fine with it.” “…Is that so? Yes, that’s… fine, right?” Why are you panicking, prince? You started spouting nonsense first. Where’s your conscience? But then, this guy really has the audacity to ask something outrageous. “…Do you, perhaps, have another man?” The guy who flirted with the original heroine is saying this now? Calm down. He’ll regret this later. All I need to do is remain a devoted fiancée until then. “What are you talking about? A woman like me… plain, not beautiful, with a gloomy personality, what man would even—” “What? Who dared to say that about you?” …You did, in the original story. This guy is acting weird. But he’s not the only problem. “My dear little sister Doris, that dress you’re wearing today is dreadful. No wonder there are rumors His Highness has abandoned you.” “Well, it can’t be helped. His Highness is too good for me anyway.” “…Hold on. Too good? Who said that? Wait, were you really dumped?” The original villainess, who also happens to be my older sister, Natalie, is suddenly interested in my love life. Why are all the original tr*shy characters growling at each other over me now?!

She died in her prime as the Queen of Song.

After being reincarnated, she becomes a simple trainee.

Losing her former glory? It doesn’t matter—no one can compete with her voice as a beautiful singer.

Mocked by her lowly birth? It doesn’t matter—her true identity is enough to make the whole world tremble.

She owes huge debts? It doesn’t matter…

A powerful boss once whispered to her, “Your debt will disappear if you become my woman.”

But the proud her would reply, “I’m sorry. I would sell my art, but not myself.”

- Description from Novelupdates