Эп. 4: Кадзуза узнаёт о выписке своей бабушки, а Чизуру падает за борт во время паромной переправы.

4

While Mami is kissing Kazuya, he remembers when they first met. When they return to the group, Kazuya receives a call from his grandmother informing him that she will be discharged from the hospital. After taking the call, Kazuya announces he and Chizuru are going to break up, which leads to a fight between him and Kibe. Kibe then calls out Mami for her behavior. Afterwards, Chizuru tells Kazuya that he did nothing wrong. Later, Kibe catches up with Chizuru and they have a conversation about Kazuya. He tells her that he has known Kazuya since they were little and despite his flaws, Kazuya is a good guy at heart. He then gives her a couple of ferry tickets he bought. On the ferry, Kazuya receives a call from Mami. While he is on the phone, a delirious Chizuru falls overboard. After he hears what happened from the other passengers, Kazuya immediately goes after her. (Source: Wikipedia)