鼓手 is read as こしゅ (koshu) and means drummer.
こしゅ
koshu
こしゅちょう
drum major
こどう
beat
こぶ
encouragement
つづみ
hand drum
こまく
eardrum
はで
showy
あくしゅ
handshake
はくしゅ
clapping one's hands in prayer (at a shrine)
みょうしゅ
spectacular move (chess, shogi, etc.)
にるいしゅ
second baseman
さんるいしゅ
third baseman
きしゅ
standard-bearer