From Manga-Heaven:

"You can do anything if you put your mind to it." That is how Mio was raised... if you could call it that... by her rather lazy guardian Reki. Born on an island she has never been away from, Mio grows bored of her everyday life... That is until Sarah comes along.

Sarah is a member of an organization that explores and manages many "Homes", islands much like Mio's. For Mio this is her ticket to adventure, excitement and the most interesting thing of all... school! But is the school ready for Mio?

Kosaki Onodera, whose family runs a Japanese sweets shop, is transforming into a magical girl in this story.

(Source: ANN)

Their city is filled with criminals and three incredible high schoolers. Yugo, Rikiya and Tusk are determined to clean up the city with whatever means necessary, even if that means using violence. During a typical night of wiping out gangs, Tusk comes across a beautiful girl held prisoner. She helps him survive what would have been a mortal wound by allowing him to see the future. Tusk takes her home where he finds that her name is Noah, she doesn’t speak at all, and has no memory. Even more fascinating to Tusk, she bears the same tattoo as the person he has been searching for years.
(Source: MangaHelpers)

We Never Learn centers on Yuiga, a student who is aiming for a scholarship because he comes from a poor family. His school gives him a condition: he can have a recommendation for a scholarship if he tutors his two beautiful classmates to help them get into the schools of their choice. Ogata may be a science genius and Furuhashi a literature prodigy — but Ogata is aiming for a liberal arts school and Furuhashi is aiming for a science school. And they're both clueless outside their fields of expertise.

(Source: ANN)