ゼッケン

number/bib

On the day of the sports day, please wear a number on your gym clothes.
It's hard because I have to prepare bibs for all the participants/

ゼッケン8番の選手
A player wearing the number 8

bib   /bɪb/　n)よだれかけ･練習試合でチーム別に着るベスト･ゼッケン

patticipant   /pɑː'tɪsɪpənt/　/pɑːr'tɪsɪpənt/　noun

★ a person who is taking part in an activity or event