The Sealed Auditorium

The unopened auditorium is said to be a special building in Kamome Gakuen Academy. It's only open once a year for the Autumn Festival, where middle school and high school first years use it to perform a play of their choosing.

66th Festival
During the 66th festival, Hanako and Tsukasa were first-years in middle school, which means their class performed a play in the unopened auditorium. Neither of them had acting roles, and only Tsukasa helped with the preparations.

113th Festival
In the current day, Kamome Gakuen begins its 113th festival, where the play "The Wizard of Oz" will be performed by Class 1-A.