Upon learning of their parents' passing, the Minami siblings—Seiya and Nagi—returned to their village of birth. With few villagers remaining, they settled into a quiet life together... But when Nagi fell gravely ill, Seiya sought help at the shrine—where he encountered a mysterious black-clad shrine maiden named Yami. To save his sister, Yami revealed that he must "unite" with Nagi. This is a tale of breaking a wish to make another come true, to save the one most precious to you.