Scared Rider Xechs

Both have the same setting base on some apocalyptic future where humankind in at odds with some inter-dimensional beings and one of the characters also happen to be one of those beings fighting for the humans. Also there is that one character that serves a special purpose for the team fighting against those inter-dimensional beings, except of course in HxH the at one character have to do something errrrrrr, let's just say something kinky to his team/ harem while the special character in Scared Rider serve as the team/reverse harem leader/mentor. 

Zaion or I: Wish You Were Here & Scared Rider Xechs both have the same setting base on some apocalyptic future where humankind in at odds with some kinda of monsters that is either alien or people being effected by a virus. Also there is that one character that serves a special purpose for the team fighting against those creatures that they may be immune or have a hidden power. Did I mention both also have that transformation to fight those inter-dimensional beings so there's that. 

Both involve a chose girl that is supposed to save the world. Both also involve two worlds that are competing to survive as well as "knights" or "fighters" to determine that.