Core Magazine Co. Ltd. (株式会社コアマガジン) is a Japanese publishing company focused on adult material, such as adult magazines and hentai manga. It also publishes yaoi titles, such as Kirepapa. The company was established in 1985 as Shōnen Shuppansha (株式会社少年出版社) by Byakuya Shobo. Core Magazine owns a bookstore chain "Core Books" (コアブックス). Source: Wikipedia (en)