yuu, whose student life living alone in a dormitory after leaving home is also coming to an end, is about to graduate. and then, on the way home from the graduation ceremony, the feelings she had hidden for her reunion with her smiling stepmother, Marina, began to smolder again. that night, Marina, who had drunk too much at a graduation celebration with just the two of them, was sent to the hotel by yuu... suppressing her feelings that were about to run wild, Marina gently kisses him as he tries to leave the room, saying "take my graduation gift..." and then the boy climbs the stairs to adulthood.