On the island of Rokushiki Jima, an annual sacred tournament called the Rokushiki Sai sees young women from the six ruling families draw on divine power to fight inside a magically sealed arena. The day-side scenario follows Nanaki, the new family head whose ceremonial role bars her from competing despite her certainty she would win. The evening-side scenario reveals the shadow festival hidden beneath the official one — a system allowing the four lesser sub-families to challenge and forcibly replace the heads of the six. Ten years ago, seven-year-old Tomoe won such a challenge through questionable means; now all four sub-families are moving against her simultaneously.