* Based on a seinen manga by Koyama Chuuya, serialised in Weekly Morning.

The anime's original story features Mutta and Hibito during one summer when they were children. During the summer when Mutta and Hibito made their promise to go to space, they met a young girl who also had a wish.

Source: ANN

Note: This anime was initially screened in Konica Minolta planetariums across Japan. It was later included on a DVD within the limited edition of the manga's volume 20, released on 22.02.2013.

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Parent story: Uchuu Kyoudai