#so i doubt my analyses will get anything completely wrong

This is the chapter where Hirano takes Kagiura to a basketball match as his birthday gift and Kagiura makes his first attempt at confessing to Hirano.

There’s twice in this chapter where Kagiura reacts in a way that confuses Hirano or Kagiura a bit. The first one is Kagiura’s reaction to getting the keychain souvenir:

To which Hirano says “…? Oh, sure.”

The second is when Kagiura explains why he gave Hirano a crepe and Hirano says that he loves that sort of thing:

To which Kagiura wonders “…Why did that almost move me to tears…?”

These two reactions are mostly surprising in their relative intensity, with Kagiura being genuinely really happy to receive a silly keychain and being almost moved to tears by a simple statement. I think both of these reactions come from the same place - how Kagiura wants Hirano to be a part of his family. We’re told how gift giving is a fairly common thing in Kagiura’s family:

It’s also in this chapter that we’re told that Kagiura loves the relationship that his parents have.

Both of the reactions are to something Hirano does that means that, for at least this aspect, Kagiura can have his parents’ kind of relationship with Hirano - he gives an extra souvenir to Kagiura just because and says that he likes this kind of thing. Kagiura’s family means a lot to him, so anything Hirano does that mirrors the aspects that Kagiura likes in his family would obviously matter a lot to Kagiura.

It’s no wonder that when Hirano said he had a lot of fun at the basketball game (another thing that Kagiura loves) right afterwards Kagiura couldn’t help but confess.