The comics are rarely graphic and focus more on the love story and relationship of the characters. These comics started with extremely close, platonic relationships between the boys that eventually turned into romantic ones. Shounen-ai literally translates into boy love.
Eventually this turned into it's own genre called shounen-ai. But in some of these early comics instead of the lead male characters falling for the girl, he became gay.
Shoujo mangas are romantic comedy-style comics aimed at girls between the ages of six and 16.
Shounen-Ai Japanese gay comics have a large female audience, in part because the genre tends to be featured as subplots in girls' comic books.