[header] How to become a manga ka [title] Take appropriate courses in high school. [step] While you're still in high school, start building your artistic skills by taking art classes. Drawing and painting would both be helpful for building your skill set to draw manga art, and even a general art class could potentially help you build skills. 
[substeps] In addition, take literature and writing courses. As a mangaka, you'll be creating a story line, as well, so make sure to spend time focusing on how to develop a story.