This is the debut game by North Box. Yuutarou is an ordinary student at Yotsuya Gakuen with a slight interest in the occult. It was the last day before summer vacation, and he still didn’t have any special relationships with the girls in his class. That all changed when his osananajimi Yuumi invited him to come to the school that night for a ‘courage test’. Being fully prepared, Yuumi suddenly had to go to the comfort room, thus, leaving Yuutarou alone in front of the door where they were about to enter. But, as he kept waiting for Yuumi, curiosity got the better of him as soon as he heard noises from the room. What awaits him will soon uncover these mysteries that are beyond human comprehension.