Gyakutama

Main character is always short for money since he's the only working member of the family after his mother death. He needs to pay the debt within a month or house will be taken for debts. He's very good in athletics, and because of that he gets a place at a super prestigious school. Since he can't get the money the proper way, he intends to get the money from naive rich ladies at school.

[From vndbreview]