It starts around 16:02 when Neji flashbacks him beating Lee. I've tried Shazam and listened to the start of every song in 2 different playlists (around 200 total, 150 different songs) so it's either in the middle of one of them or not listed. Thanks for the help!
The song was unreleased, called Broken Bonds https://youtu.be/x9K_phEPt2Y?list=PLjUUDZUvksbQ7x6Slux61wqUqf9_GhU3b
