Taisho era. This is the story of a boarding school for young ladies that stands quietly on the outskirts of town. The students there are “caged birds,” restricted from leaving the school grounds even on days off. The girls shared everything, from their loneliness and joy to their teenage melancholy. Eventually they created the “Pseudo Sisters” system—a special relationship in which two girls would exchange each other’s most valued possessions and form a sister contract until graduation. But one day, two girls who formed a contract to become “Pseudo Sisters” committed a double suicide. The two died holding the “valued possessions” said to be a symbol of the bond between them, but the teachers returned those “symbols” to their original owners and treated it as an accidental death. If we die, we can stay together forever. The wishes of these two girls who committed suicide were trampled so easily.