By Hayabusa spacecraft, for the first time, we saw the real appearance of a very small solar system body, asteroid Itokawa, which is an S-type asteroid only about 500 m in length. We had a lot of scientific results form the observation of Hayabusa. Hayabusa is now on the way to the earth and it will come back in June 2010. While working for Hayabusa, we have been considering post-Hayabusa missions, Hayabusa-2 and Hayabusa-Mk2. Hayabusa-2 is a kind of replica of Hayabusa and it will explore a C-type asteroid. Hayabusa-Mk2 is newly developed spacecraft and its target is much more primitive objects such as P or D-type asteroids or dormant comets. In this way, we are considering programmatic missions for the exploration of primitive bodies. Since there are many small bodies in the solar system, we should have such strategic approach. From 2006, Hayabusa-Mk2 is considered with the European reserchers for small bodies of the solar system. And it was proposed to Cosmic Vision of ESA with the name of 'Marco Polo.' It has passed the first selection so now we are in the assessment phase. We hope that both Hayabusa-2 and Marco Polo will be realized in the future. We also hope that we will get the clues to solve the mysteries of the birth and evolution of the solar system and the life.