When your are playing with Naruto, go to the Pervy Sage Training 1 mission. In the
battle preparation screen, you must select ninja tools, hold down R press A then
press Y. You will be rewarded with 258 EXP. Exit to the map and repeat again for
more experience (EXP). This trick only works at Naruto Pervy Sage Training 1 and
not any other stages.