MC is genuinely a good guy who happened to have a lot of money from winning the lottery and stock investments (bc JP novel logic). So to save his beautiful classmate and her family from poverty, he demanded her to give up her body to him in exchange for money to pay for her and her sister’s tuition. However, for the next few months, he doesn’t do anything which frustrates her, and eventually she traps him in her room. Turns out, he planned to become the “villain” so that she doesn’t end up doing anything s*upid or has her reputation tainted. So she becomes yandere-ish bc her bestie told her the MC’s actual plan