Hyouka no Gen'ya -Eternal Waltz-

Main character temporarily returns to his icy hometown after two and half years. He reunites with childhood friend and goes to the closed school which bears so many nostalgic memories. Protagonist's frozen heart starts to melt little by little in the familiar classroom. They young people meet a strange girl in this abandoned building, and it becomes a turning point in their lives.

[From vndbreview]