Iwanako

Iwanako is Hisao's former girlfriend, from prior to his initial heart attack, which occurs during her confession of love during the prologue of the story. They eventually drift apart completely during his hospital stay. In every route of the game, Hisao receives a letter from her; his response (whether he writes back, reads it completely, etc.) differs by route.

From url=http://en.wikipedia.org/wiki/Katawa_Shoujo.