Shogakukan founded Shueisha, which also founded Hakusensha. These are three separate companies, but are together called the Hitotsubashi Group, one of the largest publishing groups in Japan. Shogakukan is headquartered in the Shogakukan Building in Hitotsubashi, part of Kanda, Chiyoda, Tokyo, near the Jimbocho book district.
In the United States, Shogakukan, along with Shueisha, owns Viz Media, which publishes manga from both companies in the United States.
In Europe, manga from Shogakukan and Shueisha are published by local publishers such like Pika Édition, Ki-oon, Kana and Kazé for the French market, and Kazé, Carlsen, Egmont and Tokyopop for the German market. Viz Media Europe bought in 2009 the French Kazé Group whose activities are mainly publishing manga and home video for the French and German market.
In Southeast Asia, the company has a wholly owned subsidiary, Shogakukan Asia, headquartered in Singapore. Besides producing popular titles in English such as Detective Conan, Pokémon and Future Card Buddyfight, the company also partners with local creators such as Johnny Lau to publish comic series for distribution in Southeast Asia.
Acording to en.wikipedia.org