I've been reading this but I'm still confused who the seme is

They're not really a couple,but if they were to be one I think it would be Xixi.

me too

haha I also think the seme is XiXi, but it could be any of them or they could be reversible,.... And it really doesn't matter too much.

The true is that I think the author is never going to show sex, so it would be left to our imagination :(