Ryôtaku Maeno was born in 1723 in Edo. His personal name was Yomisu, his formal name was Shietsu, and he used the literary names Rakuzan and Ranka; Ryotaku was probably a common name. His father was Taniguchi Shinsuke, a samurai of Chikuzen in Kyushu, but he died when Ryotaku was still very young. Ryotaku was brought up by an uncle, Miyata Sentaku, a physician of the fief of Yodo near Osaka, and was later adopted by Maeno Togen, a physician of the fief of Nakatsu in Kyushu.
At first he studied the traditional style Chinese and Japanese medicine as taught by Yoshimasa Todo, but in 1769 he was introduced to Dutch medical works by Saka Koo of the domain of Yodo. Around this time he became a disciple of Aoki Kon’yo and began study of the Dutch language. In 1770 he accompanied Okudaira, the lord of the domain of Nakatsu, on a trip home from Kyushu and, obtaining a hundred-day leave of absence, went to Nagasaki to continue his Dutch studies.
In 1771, at the invitation of the physician Sugita Gempaku, he joined in observing dissections carried out on the bodies of executed criminals in Kozukahara in Edo. (According to the custom of the time, the actual dissection was carried out by menials while the doctors looked on.) Ryotaku compared what he saw with the information found in a Dutch book he had acquired at Nagasaki entitled Ontleedkundige Tafelen (1734), a translation of a German work entitled Anatomische Tabellen by J. A. Kulmus. Impressed with the accuracy of the work, he set about, with the assistance of Sugita Gempaku, Nakagawa Jun’an, Katsuragawa Hoshu, and Mine Shuntai, to translate it into Japanese. The translation was completed in 1774 and published under the title Kaitai shitisho. This was the first translation of a work of European science to be produced in Japan.
From this time on, he devoted his energies almost entirely to translation, introducing works not only on medicine but on such other fields as language, astronomy, geography, and military science. The titles include Kanrei higen, Jingen shisetsu, Jigaku shosei, Oranda yakusen, Oranda chikujo-sho, Kamsatsu kashi, and Roshia hongi. He carried out his studies and translation work under the patronage of the lord of the Nakatsu domain, who was moved by his boundless energy and enthusiasm to refer to him as our Dutch freak.” Ryotaku did not have a large number of disciples, though the group included men such as Otsuki Gentaku and Ema Ransai, and he num-bered among his friends Kudo Heisuke and Takayama Hikokuro. He died in the tenth month of 1803.