There are some ways to get him ..

1st, the easy way, recharge and buy Jonin Medal and you will get the 2stars Naruto Nine Tails Chakra ninja, buy his frags from events and upgrade his stars to 3 or 4 i forgot ..

or

2nd, the f2p way which is a good-luck-if-you-are-still-playing way, wait for 1 to 3 frags per year from Chase Missions and collect other ninja fragments for refinement and take the 10k pointer to get his frags ..

I said 6 tails not 9 tails chakra lmao. I think you all are mixed up with 9 tails. Because you get frags for 9 tails when refining 15k frags from 5 star ninjas and its 9 tail frags you get when recharging during events. I think I got a nine tails frag from chase mission once but never seen SIX TAILS appear in chase mission. As well I cant seem to find how to get it because when I have checked all the ninjas I have and havent got 6 tails doesnt even show up in the list. Im kind of curious why. I know theres a way to get it but not sure how.

I managed to get 6 frags since 2017 :p