It's a stupid Japanese thing - the 16 yr old FLs, in almost all mangas of that time. Kyoko from Skip Beat is 16 too, and I remember her telling Ren to go for his 16-yrs old romantic pursuit as girls can legally get married at that age! Ren is 20 or 21 I think. So that age gap was also quite common.
Anyway, when I find gems like this, I just disregard the FLs age. No teenager, no matter how precocious, is that smart and mature! The writers just tweak the age as per their country norm. That's what I firmly believe!

Gosh, no matter how many times I read this, I love It the same or even more each time. It't true that every time I reread this I'm older, and now with the same age as Kuze, feels a bit weird the age gap with Fuyuki, but hey I don't complain.
I almost can't find any red flag in Kuze too (if we overlook that Fuyuki IS a minor till the few last chapters) and Even if It's quite old this manga, has many qualities that recent mangas don't. I'll be black in months o maybe a year, but I'm como g back to reread again.