"Menhera Zamurai" is a manga series that blends historical samurai themes with psychological and comedic elements. The story centers on Shinsengumi captain Toshizo Hijikata, who, after surviving the Boshin War, finds himself transported to modern-day Tokyo. Struggling to adapt to the unfamiliar world, Hijikata encounters a young woman named Kiyoko, who suffers from severe mental health issues, including depression and anxiety. Kiyoko mistakes Hijikata for a "menhera" (a slang term for someone with mental health struggles) and offers him a place to stay in her apartment.

As Hijikata navigates contemporary society, he becomes entangled in Kiyoko's life and her struggles with mental illness. Despite his initial confusion and frustration, he begins to develop a sense of responsibility toward her, often using his samurai discipline and unconventional methods to help her cope with her challenges. The narrative explores themes of mental health, resilience, and the clash between traditional values and modern societal norms. Hijikata's interactions with other characters, including Kiyoko's friends and acquaintances, further highlight the complexities of human relationships and the stigma surrounding mental health.

The series juxtaposes Hijikata's stoic, duty-bound personality with the chaotic, often absurd situations he encounters in the modern world. His attempts to apply samurai principles to contemporary problems create both comedic and poignant moments. Kiyoko's character serves as a catalyst for Hijikata's growth, as he learns to understand and empathize with her struggles, while she, in turn, finds solace in his presence and guidance. The manga balances humor and emotional depth, offering a unique perspective on mental health through the lens of a historical figure thrust into a modern setting.