Naruto Shippuden: Ultimate Ninja Storm 2

Not really a guide. More of a warning to people so they don’t make the same mistake I did. After finishing the final fight, cutscenes will play and then the credits will roll. The game allows you to skip the credits, but at the end of the credits is when it tells you that you’ve beaten the final chapter and the achievement should unlock.

I skipped the credits and my achievement didn’t unlock. Tried playing the fight again. Tried watching the cutscene again (both before and after a hard reset just in case). Didn’t unlock.

So just make sure you don’t skip the credits just to be safe.