Following in the footsteps of his father, Hayashi Razan, Gahō (formerly Harukatsu) would devote a lifetime to expressing and disseminating the official neo-Confucian doctrine of the Tokugawa shogunate.

Gahō's hereditary title was Daigaku-no-kami, which, in the context of the Tokugawa shogunate hierarchy, effectively translates as "head of the state university".

[6] In 1670, the Hayashi family's scholarly reputation was burnished when Gahō published the 310 volumes of The Comprehensive History of Japan (本朝通鑑, Honchō-tsugan).

The most easily identified consequence of this transitional overture would be the increased numbers of messengers which were constantly streaming back and forth between Tokyo and Kyoto during the next decade.

There is no small irony in the fact that this 19th-century scholar/bureaucrat would find himself at a crucial nexus of managing political change—moving arguably "by the book" through uncharted waters with well-settled theories as the only guide.