The cafe is a place near to the main entrance of the school.
In Chapter 1 after having a quick chat with her friends in front of the school building, Meisa Ito, your rival, will go into the cafe and drink a can of tea, she will be alone during this time, providing a decent opportunity to kill her, but her friend Eriko Sakura will eventually join her, shortly before class starts.
Keishi Onozawa also goes in there after school.
Akari and Keishi
He buys a tin of peach tea.
In the morning, before lessons, Kumi Hideko goes there too and buys a tin of tea.