爆悦！恥妄遊戯「格闘姉妹悶々編」

Main character's plans to live by holding a dojo fail. He goes to his sister's dojo to challenge her and collapses there. After being fed, he challenges sister, and with some side support the fight ends in a draw. Then the sides to settle the dispute by running dojo again. And to reduce protagonist's chances of winning girls prepare special training sessions for him each day.

[From vndbreview]