Arknights: I Was a Legendary Mercenary, Yet I Still Met You

Back then, I thought I would die as a mercenary, until I met her.

Lemuen: Big brother, could you tell me about your past?

Li Ke: No.

Lemuen: But I really want to know.

Li Ke: I'll tell you next time. I promise, next time.

Lemuen: Then will you always stay by my side from now on?

Li Ke: Yes. Just call my name, and I'll always come to you.

Lemuen: Then do you like me, big brother?

Li Ke: Of course I do. How could I not? Who wouldn't love their adorable little sister?

Lemuen: I mean, the other kind of… um… like.

Li Ke: ?

Theresa, Lemuel, and Lemuen won't have to suffer if I can help it. The protagonist isn't invincible, and there's a touch of yandere.