It's an old-fashioned harem series. It's shameless and sleazy, but also innocent. Above all, though, it's obviously trash that shouldn't be watched by anyone with taste.
Sometimes, I liked it. The protagonist is quite good (especially in the early episodes), the girls are okay and it's capable of being funny, e.g. the "save girl from groper" mission in ep.9. Another hoot is Itsuyo's reverence for Misa's, ahem, romance masterclass in ep.7.
That said, though, the premise is contrived, the plot doesn't work and I defy anyone to reach the end of ep.12 without having fast-forwarded. (It won't even satisfy sleaze-hunters, because the fanservice is family-friendly.) Our hero, Takuma, is the boyfriend of nine Valkyries who use him for power-up love challenges. Because, obviously, what Norse mythological figures needed to unlock their battle superpowers with tasks like this:
(a) "play doctors and patients while removing your top"
(b) "hold hands for five minutes"
It's nonsense. It doesn't even make internal sense, because these nine sisters are supposedly being powered up by love... and yet they've all latched on to the same lumpen, scary-looking boy with a phobia of people. The traditional number of partners for nine girls would be nine. Not one. In practice, one chosen girl (Natsuki) gets a tsundere-ish, incompetent romance with Takuma, while her sisters are all just indulging their fetishes, sadism and personality problems.
I liked Takuma, especially in the early episodes when the show's putting more effort into his characterisation. He's huge, demon-fanged and has scary eyes. Everyone thinks he's a monster... but in fact he's a shrinking violet who just wants to hide in his room and study. Try to get sexy with him and he'll start quoting history textbooks to try to distract himself from scary reality. That's quite a funny harem hero.
The girls are fine. Itsuyo is full of herself, has a father complex and is funny. Yakumo and Futaba play games with people's heads, which makes them entertaining. Natsuki is what you'd expect from the tsundere romantic lead. Kururi is an extremely underage mad inventor and, thank heavens, gets no fanservice or sexy scenes. (That could have been a show-killer.) Mutsumi might be the nicest of the girls, although Misa's likeably human too.
The show's quite good at silly love challenges. What it's bad at is creating a plot that means anything, or villains with any weight. The battles are only there because they have to be. Takumi stops being interesting when he's heroic. I didn't buy the attempted emotional drama in ep.5, after which ep.6 plays as if the script fell in a mincer. They're cramming too many manga chapters into one episode. Bad anime connoisseurs will revere it. Here's a synopsis.
1. Battle battle battle, all the way through. (This is a battle episode, which is undoubtedly part of the problem.) Takuma's fighting to the death, losing his entire abdomen and having emotional childhood flashbacks...
2. when suddenly he's doing a Val x Love challenge with Natsuki. They have to strip naked and kiss for five minutes. (He healed himself with hitherto unsuspected magic powers. That I don't mind, actually, but I was boggling at the abruptness with which the episode throws us into Naked Sensitive Time.)
3. And then, even more hilariously, Takuma's suddenly, pointlessly back in battle when we'd thought he was tonsil-swapping. You'll think at first that the animators goofed and he's not meant to be in the scene at all, but no. He stays there.
4. There's a superpower that requires you to steal other girls' clothes.
5. Then there's a dance party where the winning girl gets to dance with Takuma. Eh? What happened to deciding things sensibly? This daft plot beat then gets thrown away when Mutsumi wins, only to cede her rights to Natsuki in a scene that happens offscreen. This episode's not interested in anyone except Natsuki, is it?
I enjoyed a significant amount of this, but I'd be wary of a second season. (I don't expect them to make one, though.) The show's at its best in the early episodes, when Takuma's at his most Takuma-ish, and in the silly Val x Love challenges. Trying to tell a story isn't its forte. Ep.12 doesn't work, for instance. It's not a functional finale, despite Takuma's emotional growth. I definitely wouldn't recommend this, unless you're looking for a low-rent laugh.