hehe thanks <3 now think abt it with me, bro... their parents marring each other when they were kids (aira 6, hiiro 7 and rinne 12) so they grew up together, creating their f-fraternal bond 🥺

but as they grow older it changes... imagine a 12-13 yo aira who just hit puberty having to deal with a rinne walking half naked around their house... a hiiro mesmerized with aira's body getting more curvy, more mature... rINNE HAVING TO WITNESS HIS YOUNGER SIBS MASTURBATING WHENEVER & WHEREVER CUZ THESE PRE-TEENS AR EXPLODING WITH HORMONES AND AND ofc he starts helping them at some point, he's a good big bro <3
it all starts with him helping hiiro cuz they share a room (aira sleeps elsewhere since he's a lady here ok), but soon aira finds out and bitches abt not being included lololol

ehehe big incest threesome 🥺🥺🥺