ETS 6 (Engineering Test Satellite), also called Kiku 6, was developed to confirm the technology required for a geostationary three-axis satellite bus system for high-performance practical satellites in the 1990s and to test advanced satellite communications equipment.

It was launched by the H-2 also to confirm the performance of the launch vehicle. It used an additional apogee stage for GEO orbit insertion, the LAPS (Liquid Apogee Propulsion Stage), but unfortunately, the injection into orbit was abandoned because of a malfunction in the apogee engine.

The ETS-VI is a two-ton-class and three-axis-stabilized satellite intended to develop the spacecraft bus which meets the requirements of satellite communications and broadcasting services in the 1990s. Additionally, it is also intended to develop the technologies for advanced satellite communications in the future. The preliminary design and the development of the bread-board model started in 1986. The ETS-VI is scheduled to be launched by the second H-II test flight in the summer of 1994.