this chapter sorts of reminded me of ikoku nikki (airing anime now, masterpiece go watch it) where makio was talking about her middle school friends, and how nice it is to have someone who has known you and been with you for that long. I find that even as I get to know way more people in college, the people I knew when i was 14 have a way more different relationship with me.
I assume if you knew a friend from when you were kindergarten it must be even crazier, like the type of friendship that you could go a year apart and still be tight friends