It's nitpicking, but I'd end that sentence with 'sounds' rather than 'is'.She’s so preposterously beautiful that I nearly find myself wondering if Hanako hired an actress to pose as her friend before I remember how stupid that is.
The rest reads reasonably well, so you shouldn't be so hard on yourself. Lilly showing up out of the blue really doesn't seem out of character for her, especially if you consider that Iwanako was nice to Hanako already, and her apparent presence during the incident in the hallway. The part that seems a little contrived is her bringing the whole tea set, but if I were going to visit someone in the hospital, perhaps for an afternoon, I'd bring something with which to pass the time, and for Lilly that's tea.
One of the things that seems true about Yamaku in general is that the students and teachers share a kind of automatic bond with people who've perhaps had a few bad draws in the game of life. They've seen it before, or experienced it themselves, so when they encounter someone like Hisao or Iwanako who've just been punched in the face by life, so to speak, they make an effort to help. It's a theme that runs through all the different routes, some more subtly than others, and carries over into a lot of the associated fan works.
Oh, by the way, it's good to see this continue. Carry on.
. Also, the story about Cancer Girl and the kitten really struck a chord for me. Of course, I'm very much a cat person, so is it evil that I felt worse for the kitten than either of the humans 
?
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