After a long time away, the witch Wadanohara returns to her beloved great blue Sea Kingdom, a place she called home her entire childhood. Alongside her are her familiars: the octopus Fukami, the dolphin Dolphi, and the seagull Memoca. Although excited to be back home, she longs to reunite with her first familiar, the shark Samekichi, who has since broken off all ties with her.

However, her joyful homecoming is nothing but the calm before the storm. For no apparent reason, Samekichi threatens Wadanohara, telling her to leave and never return; to make matters worse, the neighboring kingdom Totsusa is on the verge of war with the peaceful Sea Kingdom. Just what is the cause of Samekichi's hostility, and what does Totsusa seek to gain from the death and bloodshed that accompanies a war?