The background to and depiction of a watershed battle in Japanese history, at Sekigahara in 1600, when Tokugawa Ieyasu's Army of the East defeated the Army of the West of Ishida Mitsunari. The story includes the intrigues and shifting loyalties of the various retainers, family members, and samurai.

Natsumi is proposed to by Yamato, a man who aims to become a fisherman to succeed his father. Her grandmother Kiyo, who raised her since a young age, broke her legs and uses a wheelchair now. Kiyo lives in a facility where Natsumi visits to tell her about the wedding. Natsumi suggests the idea of Kiyo walking along the wedding aisle with her, which encourages the week Kiyo. With that mindset, Kiyo regains hope and try to get better with the help of Natsumi