Mentha japonica, commonly known as Japanese Mint or hime-megusa (princess mint), is a perennial herb native to moist, shaded areas along streams and in wetlands on the islands of Hokkaido and Honshu, Japan. It typically grows 8-16 inches tall and spreads via thin rhizomes. This mint species has oblong leaves with entire margins and produces small, tubular flowers that range from white to pale violet during the summer months. The flowers are modest in size but can be quite numerous, creating a delicate display. The plant emits a strong, minty fragrance similar to pennyroyal, which can be quite pleasant in the garden.

Japanese Mint is valued for its aromatic qualities and is used as a culinary herb and in traditional medicine. It is also appreciated for its potential as ground cover in shaded garden areas. In cultivation, it prefers consistently moist soil and partial to full shade, mimicking its natural riparian habitat. While it can be a charming addition to the garden, it is important to manage its spread to prevent it from becoming invasive. It is endangered in some regions of its native habitat, highlighting the need for conservation efforts.CC BY-SA 4.0