Here's a canva presentation that I made some months back about common school events in America. Feel free to make a copy and add any events that I didn't include. Before getting into the presentation, you can ask the students what school events do they have in Japan (the most common answer I got was Sports Day).
What was your favorite school event? Mine was the scholastic book fair.
https://www.canva.com/design/DAFwz96-9rE/2FKa5O0cDbHP1HWDXmJ99g/edit?utm_content=DAFwz96-9rE&utm_campaign=designshare&utm_medium=link2&utm_source=sharebutton