He attended the domain school, where his father was principal, and left home in 1873 to pursue English language studies in Tokyo.

In 1876, he enrolled as one of the first students in the Kobubijutsu Gakkō (the Technical Fine Arts School), where he was able to study under the Italian foreign advisor Antonio Fontanesi, who had been hired by the Meiji government in the late 1870s to introduce western oil painting to Japan.

However, in 1900 he resigned his post and travelled to France, where he spent the next two years refining his techniques in the impressionist school.

Asai taught numerous students who later became famous in the Japanese art world, including Sōtarō Yasui and Ryuzaburo Umehara.

He also tutored the noted poet Masaoka Shiki in the techniques of western art, and was the model for a character in Natsume Sōseki's novel Sanshirō.