Comments: I have no idea why this hasn't been recommended already. Starting as a semi-canon retelling of the chuunin exams, it soon evolves into a fic that ends up blowing away many others. One of this troper's favourite things is that each character is given depth, not just a name attached an ability. That is something hard to find in fanfiction, and Lucifer Allheart has that skill.
Its grammar and writing, at least early on, leave a lot to be desired. Oh, and don't ask how the Shukaku and Gamabunta fight in the arena without killing hundreds of spectators.
FanficRecs from comments