Hi, you must enter the classrooms building (daytime), go to the end of the hallway, go up the stairs, and again go to the end of the hallway 

If you can't access it, Can you attach a screenshot of the cell phone section: Girl's Info -> Ami. And your save file in the link below?

https://www.dropbox.com/request/iAEFvUrZelO5bsfafcoY

The save file is stored here:

-Win: C:\Users\{user_name}\AppData\Roaming\RenPy\Heroes University H 0.2.1.1\

-Win: {Game_Folder}/saves/

-Android:  /storage/emulated/0/Android/data/com.huh/files/saves/

-Android:  /storage/Android/data/com.huh/files/saves/

Mac: $HOME/Library/RenPy/Heroes University H 0.2.1.1

Although we noticed that your screenshot corresponds to an unofficial translated version that might have a bug unknown to us.