If you're looking for manga similar to Girls of the Wild's, you might like these titles. All recommendations are made by Anime-Planet users like you!
Shirihama Kenichi is a weak scaredy-cat, and his status as the karate club's punching bag has earned him the name of ‘Weak Legs'. One day Kenichi meets Miu and, impressed by her skill after she effortlessly throws him to the ground, he follows her to the Ryouzanpaku dojo. There he finds five great masters of martial arts, and driven by his desire to become stronger, he begs them to accept him as their student - though it won't be easy. Kenichi endures harsh training (and injury) from Akisame - the philosophizing Jujitsu master; Apachai - the Muay Thai ‘God of Death'; Kensei - the ecchi Chinese Kempo Master; and Shigure - the weapons prodigy. Finally after proving his determination, he is accepted by Shio - the 100-dan Karate Master, who had initially wanted nothing to do with him. Now Kenichi walks the long and arduous path to becoming a master himself, all whilst trying to protect those he cares about from anyone who would dare to harm them.
The main guy protagonists start out as total wuss bags, unable to properly punch some guy in the face or kick his balls clean off. So they meet up with a bunch of hot chicks (Wilds) and a hot chick with another hot chick and manly flex men (Kenichi). But they learn about martial arts, how to defend themselves and even engage in some romantic tension while they're busy kicking ass and when they aren't breaking faces. Kenichi focuses more on ecchi than Wilds but both provide solid martial arts action and some depth behind all the bone breaking moves and styles with some great bouts of comedy; fun reads for fans of the martial arts genre.
If one thinks of harem series, the first thing that may come to mind is how the male lead is always treated horribly by his supposed love interests. However there are two series that break this trend. You have guessed right, I'm talking about Girls of The Wild's and Kanojo ga Flag o Oraretara. In both the protagonist is treated very nicely by the surrounding girls and I believe that this refreshing break from the norm is a good enough reason to recommend those series to each other.