“Pixel Mari-tan” is a Japanese Manga comic for studying English slang used in U.S. Marines, which are never taught at school. (-tan is a colloquial form of -san)
“The magical kingdom princess, 12-year old Marine(Mar-Lee-Nay, Japanese girl’s name) transforms to marine! She, a magical democratic princess, protects democracy and fights for freedom cause. [J]” with her friends A-mi-(Army)-san, Neibi(Navy)-san, Jiei-tan(comes from Jieitai, Japan Self-Defense Force).
The series, earning a cult following, has been producing series of textbooks, figures, felt badges, T-shirts, novel, cellphone site and standby images. [J]
The latest “Mari-tan’s English drill book F*ck Edition” is specialized for the word “F*ck” only. Comic and audio drama are combined to learn orthodox Marine English like Gunnery Sergeant Hartman, one of the popular internet meme in 2-channel and Nico Nico Douga. (YouTube search “Sergeant Hartman” in *Japanese* returns a lot of parody movies. Some crazy ones.)
You can listen audio sample here.
Official manga by U.S. Army for Japanese (via WSJ Japan) are being released, too. It is drawn by the same cartoonist [J] as the f*ck drill book.