There is no official for the PlayStation 2. The series officially ended on that console with Naruto Shippuden: Ultimate Ninja 5 in 2009.
However, there is a popular community-made modification (mod) called Ultimate Ninja 6 Alpha 3.0
If you don’t want to patch it yourself, look for a "Pre-Patched" ISO on Archive.org.
, which is built on the engine of the original Ultimate Ninja 5 . Story & Content of the "Ultimate Ninja 6" Mod