The angle of the feet in relation to the hips on the horizontal plane, the angle of the circumference of the skirt on the vertical plane, and the knee joints in relation to the intended walking path.
The knee joints and the hips (the right side) themselves are also both poorly crafted, and the hip error also throws the character out of balance (it enlarges her stomach, not her hips).
The environment is well crafted and the costume and pose of the character (Reimu) are great, but the perspective of the character is not sound and wrecks the pose and picture. A few quick edits and this would be great!