Manga, a type of graphic novel, represent a widely popular literary genre worldwide and are one of the fastest growing areas of the publishing arena aimed at adolescents in the United States. However, to our knowledge, there has been almost no empirical research examining content or effects of reading manga. This article consists of 2 studies. Study 1 represents a content analysis of aggressive behavior in best-selling manga aimed at adolescents. Results revealed that aggression was common and was often portrayed in ways that may influence subsequent behavior. Study 2 examined the relationship between reading manga and aggressive behavior in 223 adolescents. Manga readers were more physically aggressive than non-manga readers and also reported more peer relationships with lonely individuals and smaller groups. In addition, reading manga with particularly high levels of aggression was associated with physical aggression even after controlling for media violence exposure in other media. Implications regarding these findings are discussed.