Episode Title:
Sodachi Riddle, Part Two .
Episode Description:
Koyomi tells Ougi that five years before, he was in trouble with his grades at school, specially in mathematics, when he finds three letters in his shoe locker and upon solving the mystery that lies on them, he is drawn to the ruins where he met a girl of his age who agreed to help him with his studies, upon agreeing at three conditions: that he would never ask, or try to figure out her name; that they would only study in the ruins's attic; and that they will only talk about mathematics. Agreeing with her demands, Koyomi studied with the girl for some time, until one day she disappeared without a trace, only leaving behind an empty envelope for him. Certain that the girl from that time could be no other than Sodachi, and by the signs of domestic violence she glimpsed in the house, Ougi realizes that by that time, the house was not in ruins, but was actually the house where Sodachi used to live, and she had actually lured Koyomi there by purpose, knowing that his parents are from the police, hoping that upon realizing that something was wrong with her own parents' behavior, he would tell them, but he did not realize that at the time, which was the reason for the empty envelope she left for him as a sign that he did not help her when she needed him most. In the next day, Koyomi returns to school, knowing that he must face Sodachi once more, but he can't shake the feeling that the reason for her hatred towards him runs deeper than that.
