Some side stories in Octopath Traveler 2 won’t be immediately available, as you won’t see ones like “Tourney Champion” until you complete characters’ chapters. This one, for example, shows up after Hikari’s Chapter 2 in Montwise is done. Which means you can help a Worried Woman and a Fainthearted Youth.
You’ll see the Worried Woman not far from the staircase down to the Montwise Arena. Talk to her, and she’ll express concern over a young man who will be entering the tournament.
Head downstairs to the Arena. There’s a young man on the right near the railing. Use someone like Throne to knock him out. Doing so will trigger a story segment, and you’ll be given a chance to fight in his place.
Now, to be clear, when I fought this battle, I ended up being beaten by the foe the Fainthearted Youth would have faced. I’m unsure if it is possible to beat them. But regardless of whether you win or lose, you’ll compete the storyline.
Once the Octopath Traveler 2 “Tourney Champion” story segments are done, you’ll get 2,000 leaves and a Reinforcing Jam.
Octopath Traveler 2 is available for the Switch, PS4, PS5, and PC. A demo is available.