It was obvious from the description and the preview of this show that it was going to be a fanservice anime. Even then, it failed on this part. There have been a few decent ecchi anime that had a plot that had substance, and even shows that didnt have the best plot but were enjoyable...but this was not one of them.
There was a lot of opportunity for it to be very raunchy, with the plot basically being that there is some demon like people who use the energy of humans for their own good, and this girl happened to get this guy whose energy source is linked to him being horny. You could easily have gotten very far with just that, with him really getting into girls and the usual dirtbag stuff horny guys do on anime. But it doesnt. It is just an excuse to show boobs every now and then, but in this age of ecchi anime that isnt really new on exciting. Oh look, tiny boobs, and big boobs. Woo...
Then it changes from this girl not being really interest in him besides a power source to caring about him in an epsisode and him revealing that he has some weird hero complex that drives him to being horny, and it falls flat. There was no real character development that led Lisera to change her tune. Any other female character introduced is just to create a scene that leads to a fight so you can see boobs, which gets boring fast.
By the time it gets to some 'real' plot, some fighting thing happening in their demon world, there is no real reason to care. Okay, cool, fight some monster and shit. Some dark impact happens to the real world but it is just rushed through and barely mentioned. That itself could have been expanded a ton, yet really it was just mentioned to create drama.
The end is typical, the classic you get the girl in the end but you are still shy about being together, since Japan seems to love not really being okay with being comfortable in a relationship. The only interesting part is the frank turn down of the childhood friend who in the cliche twist is in love with him, and confesses twice.
So overal, dont bother. If you want to see breasts, you can google some and get better results.