strawweight
The lightest weight class in professional boxing, with a limit of 47.6 kg (105 lbs). Also known as minimumweight.
彼はストロー級の世界チャンピオンになった。
He became the world champion in the strawweight division.
From English 'straw' + 級 (class). The term 'strawweight' is used in combat sports for the lightest weight division.