Cherryblossom

Ouse Satsuki, a second year student of Sakurazono Gakuen receives one day on his cell phone a message from a stranger. The address of the sender is from a student on campus, but in the school there isn't any student with that name. Is the sender someone from the student council, or is it someone else?

[From YaoiOtaku]

You have to schedule your activities in order to increase your character's various parameters, with new events appearing and the affection felt by others towards you increasing as you grow stronger. The game uses the "reverse character coupling system," whereby stats changes not only occur on the side of the player character, but also on the NPCs'.

[From eBay]