I Raise Dogs in Another World

According to her teammates, Bai Yan had never had any shame. She was a little rascal, through and through. She'd yanked off her superior's wig and sold fake discs to her teammates. She feared nothing, but in another world, a little brat made her lose her nerve completely. Everyone said Bai Yan had fallen for a cute little puppy, but the truth was that she'd been cornered against a wall. He moved as if he were pinning her there, but had no idea what that gesture meant. He looked up at her, his golden eyes gleaming with ferocity, his voice still rough with the beginnings of puberty. "You owe me. You deserve to pay with your life."

Shameless big sister x puppy with a blood feud, enemies who love to fight as much as they love each other

Premise: A story about redemption.