The true end arc of Ore no Imouto. These four episodes branch out after the 11th episode of the main TV series and present an alternative version to the end of the TV series. These episodes contrast with the good end arc of the TV series, which was an original ending written for the anime, and instead closely follows the original story from the light novels.

Twenty-six-year-old Hiroto Suwa; his wife, Naho; and their old high school classmates—Takako Chino, Azusa Murasaka, and Saku Hagita—visit Mt. Koubou to view the cherry blossoms together. While watching the setting sun, they reminisce about Kakeru Naruse, their friend who died 10 years ago. Mourning for him, they decide to visit Kakeru's old home, where they learn the secret of his death from his grandmother. Filled with regret, Suwa and his friends decide to write letters to their 16-year-old past selves to set their hearts at rest. With the knowledge contained in the letter from his future self, 16-year-old Suwa has the chance to rewrite the future. What choices will he make? What will happen in this new future? [Written by MAL Rewrite]

In the year 2015, more than a decade has passed since the catastrophic event known as Second Impact befell mankind. During this time of recovery, a select few learned of beings known as the Angels—colossal malevolent entities with the intention of triggering the Third Impact and wiping out the rest of humanity.

Called into the city of Tokyo-3 by his father Gendou Ikari, teenager Shinji is thrust headlong into humanity's struggle. Separated from Gendou since the death of his mother, Shinji presumes that his father wishes to repair their shattered familial bonds; instead, he discovers that he was brought to pilot a giant machine capable of fighting the Angels, Evangelion Unit-01. Forced to battle against wave after wave of mankind's greatest threat, the young boy finds himself caught in the middle of a plan that could affect the future of humanity forever.

[Written by MAL Rewrite]

Kai, a young middle schooler, lives in Hinashi Town, a lonely fishing village, with his father and his grandfather, a sun-umbrella maker. He used to live in Tokyo, but after his parents divorced he moved back to his parent's home town. Kai has trouble telling his parents the complicated feelings he has for them, and he's lonely and pessimistic about his school life. One of his joys is uploading songs he writes to the internet.

One day, his classmates Kunio and Yuuho invite him to join their band, "SEIRÈN." As he reluctantly follows them to Merfolk Island, their practice spot, they meet Lu, the mermaid girl. Lu sings merrily and dances innocently. As Kai begins to spend time with her, he starts to be able to say what it is that he's really thinking.

But since ancient times, the people of Hinashi Town have thought that mermaids brought disaster. Something happens that puts a huge rift between Lu and the townspeople. And then, the town is in danger. Will Kai's cry for the heart be able to save the town?

(Source: Fuji Creative Corporation)