Based off the eroge by Leaf, the same studio that made the ToHearts series, it's indeed a tear-jerker. There's also a manga, but it's not very linear and chronologically random. At least, more so than the anime and manga.

Not so much of a tearjerker, seriously. If you want something that pulls on your heartstrings, or watch Kanon or CLANNAD. Utawa makes for a relatively good game (my Touka, Oboro and Hakuro are imba) and not a bad anime series, but it isn't sad.

Nah Kanon and Clannad didn't get me. Air was man-tear worthy though