Ry Nosuke Koike

The provided text details the history and offerings of Gangan, a manga imprint under Square Enix. It originated as an imprint for Enix before the company's merger with Square. Gangan publishes various manga anthologies catering to different demographics in Japan. These anthologies include popular series that have been adapted into anime. The comics are later collected into paperback volumes under specific brand names like Gangan Comics, Gangan Comics Joker, and Young Gangan Comics, which correspond to their original serialization anthologies. The text then elaborates on several specific Gangan anthologies, including Monthly Shōnen Gangan, Monthly GFantasy, Young Gangan, and Gangan Online, listing some of the manga series featured in each. There is no mention of Ryūnosuke Koike within this information.