I dont really get it since I'm awake for almost 54 hours, who's the bottom???

Same bro

i BELIEVE... the older guy. but it could be left open ended. i don't mind it too much

I was wondering the same thing at first! I think Naoki is the bottom, since Minato asked him how his body was afterwards.

Naoki is the bottom :)
In panel 12 (for instance) you can see that Minato is asking him if his body is ok.

Thanks for clearing it up you guys! ヾ(❀╹◡╹)ﾉ~