Mary and Masaaki are step-parents. - Masaaki was desperately trying to suppress his sexual desire because Mary was beautiful, close in age, and full of motherly qualities. - However, the more Masaaki suppressed his lust, the more his mind and body weakened. - Masaaki couldn't bear it anymore and decided to leave home, and in the end, the three of them decided to go on a hot spring trip together. - With this, Kipari and Masaaki should be able to cut off their feelings for Mary, but...