class reunion, alumni reunion
この前小学校の同窓会に行った。
I recently went to a reunion for my old elementary school classmates.
同窓会、何人くらい来ると思う？
How many people do you think will come to the class reunion?
トムは先週高校の同窓会に行った。
Tom went to his high school reunion last week.
“サンノク高校同窓会へようこそ”
Welcome to the Sannok High School Alumni Association.
— オールド・ボーイ (2003)