We are studying innovative space systems, including very small 1kg pico-satell ite to large "Furoshki-satellite" of 1km size, conceptuarizing new ideas on mi ssions, systems and how to operate them. We have already developed, launched and successfully operated three pico and nano-satellites, "XI-IV", "XI-V" (1kg CubeSat) and "PRISM"(8kg remote sensing satellite), with which we lead the wo rld research scene on nano-satellites. Current target is how to develop not o nly "educational" but also "really practical and useful" nano-satellites, and we are pursuing technology innovations and mission creations for less than 50k g satellites. "Nano-JASMINE," a satellite with astrometry mission, is one exa mple of such practical satellites. We are also conducting basic research on c ontrol engineering and artificial intelligence, in order to realize more dependable and intelligent space systems.