Natsume-Atari Inc. (ナツメアタリ株式会社, Natsume-Atari Kabushiki-gaisha) is a Japanese games production company responsible for the development of Eiyuden Chronicle: Rising.
Natsume-Atari was founded in 1987 as Natsume Co., Ltd. . In 2013, Natsume Co. renamed itself as Natsume-Atari following a merger with Atari that year.
As a software developer, Natsume-Atari was responsible for the development of many games since the NES era, including Wild Guns and Pocky & Rocky, and also of many licensed games, including Power Rangers and Medabot games. More recently, they were involved with the development of the Wild Guns remake, Wild Guns Reloaded.
On August 29, 2020, it was revealed that Natsume-Atari would be responsible for the development of Eiyuden Chronicle: Rising.
Split from Natsume Inc.
Natsume Inc. was established as an American subsidiary of Natsume Co. in 1988.  The companies split in 1995, with both companies retaining the Natsume name in their respective countries. The American Natsume Inc. is well known for publishing and later developing the Harvest Moon games.
Today, they are completely unrelated, but may still work together in specific projects, with the most recent case being the American Natsume Inc. publishing the Natsume-Atari's Wild Guns Reloaded.