I hadn't seen any wallpapers of this anime/manga so I decided to make one. =d
The anime/manga is Tegami Bachi. The character in the wallpaper is named Gauche Suede.

Warning SPOILER! To explain the words: in the story, Gauche is a letter bee who works for the government delivering letters for the people and guarding the letters from giant monsters called gaichu. The letters carry in them the heart of the people so letter bees protect them from gaichu (who want to devour the hearts) by shooting their own hearts out in the form of bullets. As the story goes on, Gauche loses his heart in the process...

Credits
google
sinisterfonts.com