side of a sumo wrestler's mawashi
Refers to the part of the mawashi (belt) that passes over the hips on either side of a rikishi. Used in sumo terminology.
Grabbing the side of the mawashi is a foul.
彼は相手の横褌に手をかけた。
He got a grip on his opponent's side mawashi.
Compound of 横 (yoko, 'side') and 褌 (mitsu, 'loincloth' or 'fundoshi'). The reading みつ for 褌 is a specialized sumo term.