Where to start with this anime... Basically, it's a pretty average, not very original ecchi/harem anime that involves a high school student named Yuuri Mito finding a relic of some sort that was dug up, and then later coming back to it at night and bringing his friends with him to the relic to perform a ritual on it. One of his friends, who is named Ameri Kawai, ends up getting on a motorcycle that Yuuri brought earlier in order to leave, and instead ends up smashing into the relic with it on accident, breaking it and causing a bunch of evil/misguided beings called "Tayutai" out, along with a white haired little girl with a giant hammer called Mashiro Mito.
This girl shows up and almost instantly begins running around acting crazy, trying to beat up tiny little Tayutai. After losing a quick battle, the tiny Tayutai reform/learn the error of their ways and become allies almost instantly. After a short while, Mashiro suddenly grows up into a grown woman due to regaining her energy, and decides she likes Yuuri and that she wants to marry him. That's basically the gist of the beginning of this anime. It's uh...very fast paced and doesn't go too much into character development or anything due to the fact that there are only twelve episodes, but I guess that can't really be helped.
As stated earlier, the story in this anime is very original and although this is just a matter of opinion, there was not really any "twists" that you wouldn't have been able to predict unless you were extremely new to anime in general. If you want me to sum the main story up...some girls and a guy beat up three evil Tayutai in between going to school and doing normal activities. Now I know I have been pretty harsh on this anime, but I honestly cannot say that this anime was that great. That doesn't mean that it is terrible, it just lacks a lot of things that could have been there if there were more episodes.
One thing that made the anime a little worse, is that except for one or two minor weak villains, all the main villains end up becoming good after one or two fights and except for the aforementioned one or two minor weak villains which were killed by stronger villains almost instantly, everyone lived and was happy. Well, one good thing to say about this anime is that at least I got a good laugh out of a certain scene involving Mashiro and panties in episode 5. Ahem, skipping ahead to the ending, the ending was sort of sad yet not enough to make me cry or have to hold any tears in. It did manage to keep my interest and I didn't want to pause it to ruin the "moment" at least.
Anyway, if you are expecting this anime to have impressive fighting scenes, good character development, or a bunch of interesting characters in general, I would suggest not watching it. If you are perhaps bored, like ecchi and harem anime, and like anime as long as the character design is good, then this might be for you on a rainy day.