Superbird-C2, known as Superbird-7 before launch, is a geostationary communications satellite operated by JSAT Corporation and designed and manufactured by Mitsubishi Electric on the DS2000 platform. It was the first commercial communications satellite built in Japan.
It was originally ordered by Space Communications Corporation, but it was later merged and absorbed by JSAT Corporation, and by the time of the actual launch it was a fully used Superbird-C2 as a replacement for Superbird-C to provide communications services to Japan, Eastern Asia, and the Pacific Ocean.

AMC-21 is based on a STAR-2 platform that provides 4.4 kilowatts of power for the communications payload. The platform will support a 15-year on-orbit mission life. It carries 24 J band (IEEE Ku band) transponders, which will be used to broadcast television signals to Canada the Caribbean, Mexico, and the United States.