But whatever... Soyon's age wasn't mentioned, but she is the childhood friend of that other guy, so maybe her age is 12 too.... I'm guessing puberty got started early.
@Det If you were an extremely long-lived, intelligent apex monster, currently 500 years old and counting, you would also probably have some kind of irreplaceable treasured hoarded. Most material ones might feel meaningless, but immaterial ones likely would feel precious.
@nyaasar I've been in this situation (manga-comment) a few times, and I have to say the same thing every time. I first noticed my classmates (plural) wearing a bra in 5th grade (11yo). And in 6th grade at least 2 of them were definitely bigger than this girl. Notice other girls here aren't quite as developed.
So personally I don't have an issue with 2/3 girls out of 15 (if we go for a 50/50 ratio) being somehow developed. What does bother me a bit is that they don't LOOK 12. Body proportions, face shape, etc. The boobs are just an extra.