The most notable landmark on the Wakeijuku grounds is the old Hosokawa Marquis residence called “The Mansion”, built in 1936 by the 16th generation of the Hosokawa House.
1739 (Genbun 4): Hosokawa Etchū-no-kami of Higo was killed in Edo castle by Itakura Katsukane, and the killer was ordered to commit suicide as just punishment; however, Shogun Yoshimune personally intervened to mitigate the adverse consequences for the killer's fudai family.
He turned to historical fiction in his later years, with the novel Hosokawa Garashiya fujin (1949–1950), based on the life of the famous Christian convert Hosokawa Gracia.