Near the beginning of the game you will be given a mission to find an imposter of Naruto leading you to meet a Cursed Jutsu Master who asks you to find his many cursed dolls that are replicas of playable characters in the game. As you progress through the game, more cursed dolls will reveal themselves and their locations are showed in the descriptions in the menu. Go to "Confirm Events" and from there select "Wanted List". After finding all the replicas on the Wanted List, you want to return the cursed dolls to the Cursed Jutsu Master so he can reveal to you the last replicas that are still out and about. Keep returning those dolls to him immediately until he has none left for you to reveal.
Here is the twist - after you finish the Wanted List he will betray and ambush you with 3 battles of cursed dolls and then escape. Lady Tsunade will then send you a letter through your messenger bird about his location in "Orochimarus Hideout." There you will face a couple more curse doll ambushes and finally a battle with a cursed doll replicating Sage Mode Naruto. After defeating him you should get your achievement.