You need to start the singleplayer and run to this section of the map in konoha
then you run to the left corner , there will apear a frog named Gekomatsu talk with him and he will give you a statue of a frog and you need to gather chakra fragments .1 Chakra fragment is 20 points and you will need to gather them until the frog statue color changes . When that happens go talk to Gekomatsu again and you the cap is resetted to a higher point . after repeating that over and over you will get the 5000 points cap .After you reached 5000 points talk to Gekomatsu and he will ask you to go to the west of the land of lightning for a strange chakra fragment .
when you reach the spot you start a new chapter Fragment : True legend - The Uchiha brothers .
first you kill some zetsu's after that you have to defeat Tobi . when you complete those 2 missions you unlocked the boss battle vs Sage Kabuto .

repeat this run over and over and you will get you Sage Kabuto in no time :D !
If the video doesn't work http://www.youtube.com/watch?v=30_B-nSaWjY&feature=youtu.be

just contact me on steam and i will awnser your questions asap

the route to go towards the land of lightning to find the strange chakra fragment
first you need to stand on this spot in konoha
this video shows the route