I guess they forgot to add the ecchi and harem tags because those cover arts are "No plot, just fanservice" 101. Just slap some big tiddy harem girls and hide the MC in the corner for maximum profit.
Description is about as generic as revenge plots get, everyone is evil for evil's sake. First chapter was pretty bad, with the artist going all over the place and the MC looks like your typical naive idiot. I'll give it a few more chapters but I don't see this getting any better.
Edit: Also, I see that the artist was a fan of SAO's Kiriko, because the armour and hairstyle look quite similar in the covers.