monpe
A type of women's work pants from Japan. They are also considered to be a type of hakama pants.
The waist is loose to allow the hem of a jacket or other outerwear to be tucked inside, and the ankle cuffs are tightened with strings for ease of movement.
While they were originally used for agricultural labor in the Tohoku region, during the World War II, the Ministry of Welfare encouraged all women in Japan to wear them, and as the state of the war worsened, their wearing was substantively enforced and made mandatory for fire fighting work during air raids.
On pixiv, this tag is often used for pants of Fujiwara no Mokou and Kazami Yuuka (PC-98).
If you try searching this tag on pixiv, you will find chaotic mixture of war-related artworks and Touhou illustrations.
-- from pixiv encyclopedia