S01E17 — Family Discount

In a flashback, Marco and Ai are abandoned children who meet in the commercial tower, grow up in Kamado's orphanage and eventually fall in love. Yuki chooses to take Yuno's hand, while Marco and Ai run to the crumbling tower's roof with Yuki's father, intending to jump off with parachutes. Yuno catches up to them and once again tries to fight them alone, while Yuki hides and attempts to help her with his diary's predictions. Yuno loses and has her phone taken away, but it turns out to be Marco and Ai's decoy, which distracts them with false predictions. As a result, Yuno manages to critically injure Ai. Yuki's father grabs one of the two parachutes and escapes the tower, but he runs into Yuki's mother, who has been informed of the situation by Nishijima. When she threatens to turn him in, he stabs her. Yuki, Yuno and a dying Ai are trapped in the wreckage, but Marco attempts to free Ai despite having been mortally wounded himself. With Yuki and Yuno's help, the debris is cleared out and Marco and Ai die together as the tower collapses. Yuki and Yuno escape using the second parachute, only to find Yuki's mother has died. Meanwhile, Nishijima has been unable to find Kamado's Future Diary server.