The fact Chiyoko spent her life chasing a shadow is enough to get you weepy-eyed, but then the final scene in the rocket and the line "After all, it was the chase I really loved" accompanied by Susumu Hirasawa's "Chiyoko's Theme Mode 2" is a full blown tear jerker.
The moment she says the line above and the following song, "Rotation (lotus 2)" combined with the sudden credits can make anyone cry.
Chiyoko just missing the train that her artist is on. Also seeing him go through the prison doors and only arriving just as they close. In both cases her desperate screams say it all.
The long journey to Hokkaido, which turns out to be all for nothing.
Finally learning of the artist's fate.
The fact that Genya hid his feelings for Chiyoko for thirty years. One would think he would deliver an Anguished Declaration of Love for her on her deathbed, and yet all he says to her are words of encouragement to find the man she loves in the afterlife. Seeing him brought to tears for the woman he loves is heartbreaking, not the least because she has no idea he's in love with her, and never will.
Try to watch the ending scene (and the cop's confession) without breaking into tears.