KDDI Corporation (KDDI株式会社 KDDI Kabushiki Gaisha?) (TYO: 9433) is a Japanese telecommunications operator formed in October 2000 through the merger of DDI Corp., KDD Corp., and IDO Corp. It has its headquarters in the Garden Air Tower in Iidabashi, Chiyoda, Tokyo.
KDDI provides mobile cellular services using the "au by KDDI" brand. ISP network and solution services are provided under the au one net brand, while "au Hikari" is the name under which long-distance and international voice and data communications services and Fiber to the Home (FTTH) services are marketed. ADSL broadband services carry the brand name "ADSL One", and IP telephony over copper is branded as "Metal Plus".

Type:    Public (TYO: 9433)
Industry:    Telecommunications
Founded:    June 1, 1984
Founder(s):    Kazuo Inamori
Headquarters:    Chiyoda, Tokyo, Japan
Key people:    Takashi Tanaka, CEO
Products:    Fixed line and mobile telephony, Internet services, digital television
Revenue:    Increase US$ 41.30 billion (2012)
Net income:    Increase US$ 3.1 billion (2012)
Employees:    18,418 (2010)
Parent:    Kyocera (12.76%), Toyota (11.09%)
Subsidiaries:    KDDI R&D Labs, KDDI Network & Solutions, Kokusai Cable Ship, 
Okinawa Cellular Telephone, KDDI America