Ōno is best remembered by fellow professional linguists for his work, following in the wake of his mentor Shinkichi Hashimoto, on the kana writing system and phonology of Old Japanese, published in 1953.

He also collaborated with Takai Ichinosuke and Gomi Tomohide in the production of important editions of two early classics of Japanese literature, the Man'yōshū (1957–1962) and the Nihon Shoki (1965–1967).

Ōno made a significant contribution to the field of Japanese quantitative linguistics by indicating a statistical relationship, known as "Ōno's lexical law", between the category of classical Japanese literary works and the rate of usage of word classes in their lexicons.

[2] His theory has been severely criticized by prominent Japanese Indologist Tokunaga Muneo,[3] and by other comparativists like Kazama Kiyozō.

Ōno's attempt to confront his critics, in the article cited here, is successful in disarming Roy Andrew Miller's critique but said to be failing to answer the general charge, made much earlier on his previous theories about an Austronesian origin for the language.