An utterly fantastic series, featuring both Tomoko's signature incredible writing, and her feel for real, multifaceted characters trying to deal with their own experiences, and her incredible art: by the lord, the table of contents in volume two is beautiful.
It's hard to see, sometimes, past our own issues that we are dealing, or trying to deal with, to see the issues others are struggling with. So rarely do we do so, and sometimes, when we try, we accept their "I'm ok." as fact, without digging any deeper, reasoning: "If they weren't, they would tell me." But we know, deep down, that no one ever wants to inconvenience someone by being the person to say "No, I'm not ok." Even less do we want to be the one put in the spotlight, ill equipped to help someone who confides in us.
The truth is that it's hard to help another human being on the edge. And sometimes, if we stop digging, thinking our paltry efforts enough, we pat ourselves on the back for helping, oblivious to the still-existant turmoil we ignore. I think this was at the front of her mind when she wrote the afterword, specifically "I never want to give up on trying to be a good person." Because, just because we helped out once, doesn't mean we don't need to help out again.
To end, I'm surprised to see so many interpreted the end as Hibari living: I thought the black backgrounds, the repetition of "I held my breath to be ok" and the afterword made clear her miserable fate.