Since the goodreads entry is in japanese, here is an english synopsis: Hida Kizuna was suprised when he was called to the Ataraxia Academy, Japans center of millitary strength against the "Another Universe", that since some years frequently starts attacks on planet earth. He is even more suprised when he learns, that he is the only male owner of a "Heart Hybrid Gear", a special battlesuit-power to fight against the "Another Universe". And he sure is even more suprised when he suddenly is surrunded by girls, all Hear Hybrid users, that have to rely on him fillng their Heart Hybrid Gears with the necessary power for battle. Guess what, the way to do that is by making them feel pleasure.
Seems like I always start to read Ligh Novels when it´s summer and I´ve nothing better to do. This time I started "Masou Gakuen HxH", due to the anime coming out in short time, and I just wanted to have the experience of reading a light novel an then shortly after watching its anime adaptations.
The novel is ... solid. Remember, I judge by light novel standarts, not by normal standarts. Light novels are most of the time written in a different style, that sometimes seems confusing and silly to us westerners. I´d go that far and say that you need more imagination to read a light novel than to read a normal western novel, due to its lack of description.
This book is kinda hard to rate, because it is a novel with its focus on ecchi, and ecchi novels aren´t specially known for great characters, good world building or a gripping story, but the goal that the book had - giving me a good ride with many ecchi moments - was achieved, so even as the novel suffers from the ecchi-novel-syndrom, I´ll give it four stars. It could have been five stars, if there would have been any funny moments in it, because i just love funny moemnts in ecchi novels.
More or less what you expect from the genre and somewhat reminiscent to: unlimited fafnir, high school dxd and Magic swordsman and summoner. However, has mecha as a sub theme. My option was its somewhat lacking compared to the aforementioned titles, and therefore only a 3 star.