Maybe the young one is as thothy as the older one. But at least she talks with her love interest, instead of treating him like air and basically using as a living dildo till she bashed into his house/family XD.
Well most guys get to decide what they want to do in life. But if youre targeted by women in Mana's bloodline, your fate is sealed as a seeder and provider for the rest of your days.
Like I said before, it's made clear how Mana takes after her mom...her mom was smart enough to only go after Air-kun on her safe days until she was ready to get pregnant.