If you're looking for manga similar to Hammerboy, you might like these titles.
Humanity has abandoned the earth and now lives in giant islands in the sky. The main character Nina hunts sky beasts with her talking cat called Cake. The defeated beasts turn into sky gems which are highly valuable items. Though when the ship she's on is destroyed by a massive sky beast it leads them to an unknown island with many mysteries.
In a world consisting of many floating islands, a young man named Gran has dreamed of taking to the skies and exploring them since his father disappeared years ago, leaving a message for his son to meet him at Estalucia, Island of the Astrals. When a mysterious girl named Lyria literally falls out of the sky trying to escape the evil Erste Empire who held her captive, her life becomes entangled with Gran's and his long-awaited journey finally begins. Together with their companions, former imperial soldier Catalina and the baby dragon Vyrn, they take to the heavens, exploring the many mysteries of their world while trying to avoid being captured by their enemies.
"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?
Set in the fantasy world of Material Puzzle, a manga done by the same author, Berji, Shuga, and Chrim live peacefully on a sparsely populated island. Berji and Shuga have unique talents that allow them to tame animals called Deathleon. On one peaceful day, an uninvited large ship arrives at their island. The ship belongs to the "Ironclad Giant" Suppression Team, and with them, they brought a piece of an Ironclad Giant. What this ship and its crew brings to the inhabitants of the island may change the world forever.
A tropical trio of lovely ladies undergoes survival training in the south! Three second-year high-school students from a military academy – tomboy Kasumi Minami, ditzy airhead Raika Utsuri, and dependable Subaru Toma – are stationed for survival training in Nonamimi, an uninhabited island in the southern seas. The girls find out that their wild tropical army life is fraught with all sorts of problems from day one! Will they be able to carry out their mission, and graduate in one piece?!
One day, while at sea, Link’s raft is struck by lightning in the midst of a fierce storm. He awakens on a strange island in the company of a girl named Marin who looks an awful lot like Zelda, and isn’t sure how to get back to Hyrule. However, when a mysterious owl instructs him to travel to the Woods of Mystery, Link finds himself on a grand adventure to find and awaken the ‘Wind Fish’ so that he may return home.
Takes place post-timeskip, showing the cast in SD/chibi form and featuring their hilarious antics around various islands while out in the sea.
To find the end of the sky and sea, we went on a journey aboard the flying island Isla. A boy who lost everything in the revolution. The lonely girl who calls the wind, who became the revolution's symbol. The young pilots set out aboard the flying island Isla to find the end of the sky. Friendship, love, adventure... and each of them have something they want to protect. An epic story of love and dogfights begins now.