The target asteroid of Hayabusa2 is (162173) Ryugu, 1999 JU3 in the provisional designation. Hayabusa2 will arrive at this asteroid in June - July 2018. In this summer, we have a opportunity to observe Ryugu, so we set up "Ryugu Observation Campaign" from July 1 to August 15, 2016. This is the last chance to observe Ryugu before Hayabusa2 arrives there.
However the maximum apparent magnitude will be just 18th mag (Fig.1), so it is rather dark. Maybe you need a telescope with the diameter of 1m or so. Or you must follow the motion of Ryugu with your telescope. Therefor the observation will be rather difficult, but please try it if you can. Good luck!-
Fig.1 Information related Asteroid Ryugu
June 21, 2016
Ground-based Observation Team, Hayabsua2 Project