Natsuki和其他女孩不一样。 她有一根魔杖和一面变形镜。 她可能是女巫，也可能是来自另一个星球的外星人。 Natsuki和她的堂兄Yuu一起在长野的野山中度过她的夏天，梦想着另一个世界。 当一系列可怕的事件迫使两个孩子永远分开时，他们做出了承诺：无论如何都要活下去。 现在Natsuki长大了。 她和她的无性恋丈夫过着平静的生活，假装是正常人，尽可能地活下去。 但Natsuki家人的要求越来越高，她的朋友们想知道她为什么还没有怀孕，而Natsuki童年阴影也被换起来了。 逃离童年时代的郊区，Natsuki前往山区准备与Yuu重逢。 他还会记得他们的承诺吗？他还会帮她遵守承诺吗？

Natsuki isn't like the other girls. She has a wand and a transformation mirror. She might be a witch, or an alien from another planet. Together with her cousin Yuu, Natsuki spends her summers in the wild mountains of Nagano, dreaming of other worlds. When a terrible sequence of events threatens to part the two children forever, they make a promise: survive, no matter what. Now Natsuki is grown. She lives a quiet life with her asexual husband, surviving as best she can by pretending to be normal. But the demands of Natsuki's family are increasing, her friends wonder why she's still not pregnant, and dark shadows from Natsuki's childhood are pursuing her. Fleeing the suburbs for the mountains of her childhood, Natsuki prepares herself with a reunion with Yuu. Will he still remember their promise? And will he help her keep it?