Since the start of the manga, the author accomplishes catching the reader; personally, my favorite chapters are 2 and 5.
Talking about the so mentioned chapter 4, i think the use of the metaphor of the AFO makes it rawer (and innocent) and it shows how this mangaka can turn the situation very well, I don't want to spoil the chapter but i really think some people may misunderstand this chapter taking it as cruel or tactless, and this chapter could not be anything less than that, it is a perfect example of how the trauma works in children and how this can influence the perception of things that they may have, a book that re me to this chapter is running with scissors it shows how trauma works on kids and how innocent and distant this is perceived, and I don’t think this chapter is insensitive it’s just realistic and not excessive, of course, you should be careful with this chapter since it’s very sad and could be triggering for some people. And something i must mention is the last quote of this chapter “even you sora, weren’t you planning to show them to me?” i think that part was so heartbreaking, because i realized that he is conscious about things probably a part of him is conscious about the feelings of his friend towards him, about the intentions before the SA but at the same time he was incapable of showing them and idk i just really like the last quote and i think is something to have in consideration reading this that some part of him is really scared and knows exactly was is going on but the mechanism it’s to ignore and think its UFOs i know its obvious i just wanted to mention it.
However, you must read kimura's other works if you like these topics and the psychological consequences, she knows how to treat these topics in a tactful way so innocent and tender, but serious in the moment that is needed, it was a roller coaster of emotions it gave me goosebumps, happiness, and i was so confused in some parts, especially the chapter 2 and 4, they were in different ways scary, second was so unexpected and almost unbelievable and 2 well you know.
(P.S, sorry if my english sounds rusty or weird)