He comes from the real world, so I'm hoping he comes up with a good prosthetic for his leg so he can move around well. In a battle world like that it always amazes me in manga and stories where they just never thought to attach wood. Heck, it's a world of magic, right? Pop a golem or something onto the leg, there is zero reason to not be able to regain normal life.
And holy cow, those girls... it's pretty clear how broken they are over this. I really hope he starts recovering and they start to process/adjust properly, getting help. Which leads me to my next thought, I'm pretty sure I've only read one manga .. which I can't even remember the name of.. but only one where they had proper mental help at the Adventurer's Guild. This seems like a perfect reason to have it. I wouldn't want to live as that guy with girls who turned into soulless husks throwing themselves at me hoping to appease my damage with their bodies. That'd suck, it's like even worse than pity but instead they'd be using his body as their own self-punishment. That'd be horrific for all parties involved.
Hoping in the next few chapters things start to turn around.