The Cool-Headed Senior Sister Is Hounded by That Yandere Demon Lord

Female-led romance, strong heroine, one-on-one, both leads are chaste.

Yin Jin transmigrates into a book and becomes the senior disciple of Wangchen Mountain. Being the senior disciple has plenty of perks. For one thing, she can keep up her aloof image and ignore everyone. Yin Jin is quite pleased with that. The only thing she isn't happy about is having to win over her junior fellow disciple. Because he is... far too pampered and unreasonable. He gives her a real headache.

Then, later...

“Senior Sister, my hand hurts. I burned it making food for you...”

“Senior Sister, I'm so sad. You won't pay any attention to me ( •̥́ ˍ •̀ू)”

Yin Jin thinks this must be... love