Kusaka Gensui

Kusaka Gensui (1840–1864) was a bakumatsu loyalist and a central figure in the sonnō jōi (revere the emperor, expel the foreigners) movement of Chōshū domain (present-day Yamaguchi Prefecture). As the brother-in-law of Yoshida Shōin—husband of Shōin's sister Bun—he received instruction at Shōka Sonjuku and is regarded as one of Shōin's disciples who most faithfully inherited his thought. Alongside Takasugi Shinsaku, he was called 'Shōin's twin pillars' and spearheaded Chōshū domain's anti-shogunate movement.

Gensui was born into the family of a Chōshū domain physician and from youth studied medicine, sinology, and military science, demonstrating exceptional talent. After becoming a student of Yoshida Shōin, he deeply resonated with his ideals and devoted himself to Shōka Sonjuku's activities. His marriage to Shōin's sister Bun transcended mere family relations and deepened his sense of identity as an inheritor of his teacher's thought.

Gensui's greatest inscription upon bakumatsu history was his participation in the Shimonoseki Bombardment (1863), when Chōshū fired upon foreign warships, and his subsequent role in the Kinmon Incident (1864). In the Shimonoseki Bombardment, Gensui, as a sonnō jōi advocate of Chōshū domain, actively led the shelling of foreign vessels and heightened international tensions. In the Kinmon Incident (Hamaguri Gomon Incident), he led Chōshū forces in an assault on Kyoto and clashed with the combined Satsuma-Aizu army defending the imperial palace. In this battle, Chōshū forces were defeated, and Gensui died by his own hand in a besieged residence. He was 25 years old (24 by Western count).

Regarding the Japanese sword, Gensui, as a Chōshū samurai, possessed training in swordsmanship and, as a bakumatsu loyalist, constantly wore a blade. The spirit of 'one sovereign, myriad people' and 'grass-roots uprising' inherited from Yoshida Shōin infused Gensui's sword with profound purpose. Through his studies at Shōka Sonjuku, the sword transcended its role as mere weapon and became a symbol embodying the sonnō jōi cause. Gensui's death by his own hand in the Kinmon Incident is remembered as embodying the resolve for martyrdom his teacher Shōin had demonstrated.

The vision of a new Japan envisioned by Yoshida Shōin, Takasugi Shinsaku, Kusaka Gensui and other Shōka Sonjuku loyalists was realized after their deaths by Itō Hirobumi, Yamagata Aritomo and others. Gensui's brief yet intense life stands as a foundation of the Meiji Restoration, a historic watershed.