In the northeastern part of Hiwatsu, an island nation, there unfolds a riveting tale within the domain of Mizuho. On the day of the feudal lord Saku’s wedding, Isaza Ukano, his younger brother, stumbles upon a female Gritborn—entities known only from fables—and is coerced into a certain pact…?! An engrossing saga of war and romance, depicted by Iroha Kohinata, is about to begin!