A 13-year-old woman was underwent transthoracic two-dimensional echocardiography (2DE), which revealed that only a small anterolateral papillary muscle was observed in the left ventricle (LV). Additional transthoracic three-dimensional echocardiography (3DE) revealed the posteromedial-papillary muscle which has not correctly delaminated from the LV wall and directly connected to the mitral valve leaflets without tendon chordae. She was diagnosed as a parachute-like asymmetric mitral valve rather than a true-parachute mitral valve. It was difficult to understand the precise anatomy evaluated by the 2DE. However, additional 3DE provided helpful information to reveal the exact characteristics of papillary muscle tissue.