In the landscape of modern visual novels and light novels, Celica Magia

"C-Celica?" Yuji stammered.

Now, the girl who wouldn't even hold his hand is acting like they’ve been married for ten years. She packs him elaborate lunches, calls him "Darling" with a straight face, and violently strikes down anyone who looks at him wrong. Leon is terrified, the Kingdom is confused, and Celica is dying of embarrassment on the inside, unable to revert the spell until she admits her real feelings.

She stared at his back. Then she laughed—a broken, wet, utterly tsundere laugh. “You’re still an idiot. Fine. But if we die, I’m haunting you forever.”

Celica Magia ~Tsundere Childhood Friend Becomes a Dedicated Onahole in the Royal Capital~

You can watch her in action on Crunchyroll, where the anime adaptation is available. Akashic Records: Fantasy Action Anime Review