Mahou no Rouge Lipstick

A young gradeschool girl can only envy her already teenaged friend's boyfriend. But when she meets a magical salesman pig and receives a magical lipstick (containing another magical sidekick creature, if that's not enough magic for you), it's time to magically gain some years and hit on the boy! But what if the spell breaks and he realises he's been getting hot and heavy with a nasty-minded but still preteen girl? (Source: AniDB)