Crossed Lines

Crossed Lines (混線, Konsen) is the eighteenth episode of the Future Diary anime.

Summary
A year before current events, Yukiteru Amano had a crush on his classmate, Moe Wakaba, much to the displeasure of his stalker, Yuno Gasai. She chanced upon him carrying a love letter addressed to Wakaba, and resolved to keep him from delivering it at any cost.

She dressed up in a pink rabbit suit and trailed the pair when they went shopping for supplies for a school cultural festival. Although she was ultimately unsuccessful in stopping Yukiteru, Wakaba turned him down.

Yuno returned home, greeting her parents, who have been dead for a month. She recounted how they would lock her up in the same cage for the slightest imperfection and starve her. Eventually she snapped and locked them up, turning to her childish promise to be Yukiteru's bride as a source of comfort.

In the present, First mourns the death of his mother, Rea Amano, even pleading with Deus Ex Machina to bring her back. However, he informs Yukiteru that this is beyond his power, and that the universe will ultimately be destroyed when he fades away. Muru Muru says that by taking her master's place, First may save his mother and all of reality.

Kurou Amano forces his way into his old home, and his son suspects he was responsible for his ex-wife's death, but without proof, he cannot be sure. First notices his father hiding a receipt for a pawnshop and resolves to steal whatever he wants to pawn off the next day.

Meanwhile, Masumi Nishijima tries and fails to question Yuno about the skeleton found beside her parents' in the hole in her backyard.

The next day, Yukiteru follows his father to the pawnshop and then a shrine, where he finds that Kurou has obtained a telescope with the aim of taking him stargazing. The man expresses deep regret for killing his ex-wife, and agrees to turn himself in, with the condition that he and Yukiteru rekindle their father-son relationship once he is let out of prison. First forgives him and agrees with the idea.

Shortly after, one of the Eleventh Diary Owner's men stabs and kills Kurou. Other agents under Eleventh's employ turn up to kill First, but the boy remembers Muru Muru's words and discards his principles, stabbing the attackers and using them as human shields. Yuno appears and finishes off the rest of them. Yukiteru tearfully attempts to kill Yuno, but cannot go through with it. Second says that she will always be there for him.

In the Cathedral of Causality, Deus and Muru Muru watch the scene unfold.

Muru Muru's Section
Happening across a disguised Yuno, Muru Muru decides to imitate her, dressing up in a yellow rabbit suit. Yuno gets the demon off her back, and Muru Muru is escorted away by mall security.