| October 1987 | Natsume Inc. established in Shinjuku-ku, Tokyo |
| May 1988 | Natsume Inc. established in SAN FRANCISCO |
| October 2002 | Atari Inc. established in Kita-ku, Osaka |
| October 2013 | Natsume Inc. and Atari Inc. merged to form NatsumeAtari Inc. |
| October 2015 | Head office moved to Kita-ku, Osaka |
| June 2019 | Nippon Systemize Co., Ltd., which develops business software, becomes a wholly owned subsidiary. |
