Hybrid x Heart Magias Academy Ataraxia, Vol. 1 (manga)

Invaders from another world are attacking the Earth,and humanity's only hope lies in special armors called Hybrid Heart Gears, orHHGs. Hida Kizuna might seem unexceptional, but he has a skill that can turn thetide of battle--by getting female HHG users hot and bothered, he can replenishtheir energy!