Well, this was an interesting chapter. Hallucenigenic frog acid. I was wondering what was going on there.
At first I thought it was the mystery girl in the frog stomach. From that flashback, i'm guessing Kasumi tried to kill herself after she was picked as one of the 160. That way, Shizuku would take her place. It seems like she repressed it somehow.
I get the feeling that there is some huge plot twist that is going to happen later on involving Shizuku. Can't wait to see what happened to her and the whole world.