Mentha japonica is a species of plant in the family Lamiaceae, endemic to the islands of Hokkaido and Honshu, Japan.

Initially described as Micromeria japonica by Friedrich Anton Wilhelm Miquel, it was first identified under its present name by Japanese botanist Tomitaro Makino in 1906.

One of its Japanese-language vernacular name is said to derive from the plant's small size compared to other mint species.

[4] Mentha japonica is now generally accepted as a distinct species by taxonomic authorities,[5][6] but (as with mints generally) the exact phylogenetic tree of Mentha japonica has been difficult to determine due to the genus' tendency to hybridize readily.

[10] A 2018 phylogenetic study disputed the placement with Mentha, finding it was not closely related to the other mints within the section.

These same researchers found a close genetic similarity to Mentha gattefossei, because of which they re-proposed the classification of M. japonica within section Eridontes.

[12] Mentha japonica may be categorized as among the mints with menthol as a primary monoterpene compound (as opposed to carvone or linalool), a characteristic it shares with the majority of the genus.

[16] Viable laboratory hybridization has been documented between M. japonica and the Mentha species M. canadensis, M. aquatica, M. rotundifolia, M. spicata & M.

Other chemical constituents identified in smaller amounts include 3-Octanone, 3-Octonal, d-Limonene, alpha-Pinene, beta-Pinene, Menthyl acetate and Piperitone.