At the heart of a continent of eight kingdoms lies the Marronnier Kingdom. Its general, Baribara, has seven sons, each with a unique gift and serving as a knight commander. Bound by a single noble cause of heroically rescuing a princess someday, the brothers set out as goodwill ambassadors to the seven neighboring kingdoms. What encounters, trials, and destinies await them in these unknown lands?

Chilly finds himself drawn to Bruno, unaware that it is Princess Brunhild disguised as a man. But after learning of a string of mysterious incidents surrounding her, he begins to suspect someone is working against her. He decides to uncover the truth when something strange occurs within him. Meanwhile, Insomniac is selected as the first goodwill ambassador, and his future fiancée is to be chosen.

Insomniac accepts his engagement to Ellie, the castellan's daughter, but conflicting motives begin to emerge behind the arrangement. During a sword tournament at the castle, Swordsman and Ellie advance to the semifinals, where they face off in a fierce duel. Later, Ellie learns she has been chosen to accompany Insomniac as a knight commander aide on his journey to the Country of Long Nights.

As they journey to the Country of Long Nights, Ellie begins to notice subtle changes in Insomniac, whom she has known since childhood, that leave her uneasy. They arrive in a land where blue flowers bloom, and preparations are underway for the annual Walpurga Eve festival. But beneath its peaceful surface, Insomniac senses an ominous presence, and the country's hidden secrets slowly come to light.