K-On! is a popular Japanese manga series written and illustrated by Kakifly. The story revolves around four high school girls who become members of their school's light music club to prevent it from being disbanded. The manga was serialized in Houbunsha's Manga Time Kirara and Manga Time Kirara Carat magazines. It has been adapted into a 13-episode anime series in 2009, a second season in 2010, and a film in 2011. The series has enjoyed strong sales in Japan, with merchandise sales reaching over ¥15 billion ($192 million) by 2011.