He was a pharmacologist, student of Rangaku, author, painter and inventor well known for his Erekiteru (electrostatic generator), Kandankei (thermometer)[1]: 462  and Kakanpu (asbestos cloth)[2]: 67 .

They accompanied a cadet branch of the Date clan to Uwajima Domain in Shikoku, but eventually moved to Takamatsu where they supplemented their meagre income as a low-ranking samurai with farming.

[citation needed] In Edo, he studied with Tamura Ransui, and with his oversight and support Gennai began to cultivate natural specimens of ginseng.

While in Edo Gennai wrote a number of books, some on scientific or nature topics, some satirical novels, in the kokkeibon and dangibon genres.

He also held exhibitions of his various inventions in Edo, and came to be known to Tanuma Okitsugu, a senior official in the Tokugawa shogunate, as well as the doctors Sugita Genpaku and Nakagawa Jun'an.

In 1772, while on a trip to Nagasaki, Gennai uncovered a store of clay; this led to him petitioning the government to allow him to manufacture pottery on a large scale, for both exports and domestic use.

[5] In 1773, he was invited by Satake Yoshiatsu to Kubota Domain to teach mining engineering, and while in Dewa Province, also gave lessons in western oil painting.

[2]: 69  The most prevalent account is that he was arrested in late 1779 for killing two carpenters on the project in a drunken rage after they had accused him of stealing the plans for the mansion.

This has given rise to many theories over the years that Gennai had not actually died in prison, but had been spirited away, possibly by the intervention of Tanuma Okitsugu, and lived out the rest of his life somewhere in obscurity.

Perhaps one of the most well-known is On Farting, a satirical work which explored encounters between high and low culture in Ryōgoku, a popular entertainment district in Edo.

[8] Within this work, Gennai himself is depicted as having a "spirited" debate with a samurai about a peasant who had gained fame and popularity as a fart-ist, entertaining crowds with performances of flatulence.

For the Confucian samurai, the performance represents a serious offence against propriety and social order, whereas Gennai believes that it embodies wisdom and creativity.

Kinkichirō argues that it goes against everything that the "true sages" taught society about human decency and etiquette, but Gennai sees the fart-ist's creativity and wisdom in being able to make such useless excess into music.

Not wanting to subject his lover to eternal suffering in hell, the kappa brings back a less attractive onnagata in an unsuccessful attempt to appease Enma.

[3]: 114-5 Continuing the theme of satirical publications, Gennai's piece "A Lousy Journey of Love"[3]: 62-4  is part of Blown Blossom and Fallen Leaves, an anthology of his work compiled and published posthumously by his friend and trainee, Ōta Nanpo.