Pokemon: Cynthia's Childhood Friend, the Breeder

[Single heroine: Cynthia (Shirona/Cabbage Sister) + System + childhood sweethearts + older girl/younger boy (Cynthia is a little older than the protagonist)]

[The anime is the main background. I've played the games, but not that much. The story is set before Scarlet and Violet, since I really don't like Terastallization or the new Pokemon. Mega Evolution still looks the best.]

Si Chen's transmigration makes no sense, and he was transmigrated as an unborn baby. The good news is that his childhood sweetheart is Cynthia. The bad news is that his dad died. The even better news is that he has a System.

Cynthia: “Oh, you little brat! You're laughing at me again!”

Si Chen: “Nyeh-nyeh-nyeh!”

Professor Carolina watches the two of them squabble from a distance, smiling alongside Si Chen's mother.

Then one night...

Cynthia: “Umm... which ice cream should I choose?”

Cynthia: “Got it. I'll have grape flavor today.”

Si Chen: “Wait a second! Why are you holding grape-scented perfume when you said you were choosing grape ice cream?”

Si Chen: “Back off, back off!”