During the peaceful Edo period in Japan, Masanosuke "Masa" Akitsu, a skilled swordsman but meek in personality, is deemed "unreliable" by his employers and dismissed abruptly. This leads to Masa questioning his identity as a samurai and wandering aimlessly as a ronin. In his darkest moment, he meets Yaichi, a carefree man dressed in pink, who hires him as his bodyguard without much reason. However, Masa soon realizes that his new employer is involved in illicit activities with a gang known as the Five Leaves. Despite struggling with his own beliefs, Masa's curiosity leads him deeper into the group and their mysterious past.