This may or may not be correct, since I'm running off google translate and context clues, but it seems like the main girl finds the bowl under the bed, and finds out from... Ghosts, I guess, since they're just suddenly in her room and then they're gone. She finds out that her senpai that's been pushing her to eat more and more has done this to another girl, resulting in her death after she hits her full stomach on a table and bursts. So, then our heroine breaks up with her senpai the next day. But later, she sees that senpai has found another girl to feed.
I THINK that's what's happening at the end.