This is two-tone_hair_girl_(ohisashiburi) and is a male character. There is a slight bulge visible, and other pictures of the character show it even more clearly. Several images of the character are tagged 男の娘 on pixiv, as well, when the artist bothers to tag them. This image's 1girl tag should be changed to 1boy, and someone should probably rename the two-tone_hair_girl_(ohisashiburi) tag to something more accurate.
