KDDI Corporation is a Japanese telecommunications operator. It was established in 2000 through the merger of DDI, KDD, and IDO. In 2001, it merged with a subsidiary named Au, which was formed through the merger of seven automotive and mobile phone companies from the DDI-Cellular Group. As of 2020, it is the second-largest mobile telecommunications provider in Japan in terms of the number of contracts, following NTT Docomo. KDDI provides mobile cellular services using the Au brand. ISP network 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 services are marketed. ADSL broadband services carry the brand name "ADSL One", and IP telephony over copper is branded as "Metal Plus". Wikipedia