During the main game, you can talk to Silvia to request a friendly with teams you defeated in the regional and national Football Frontier Tournament. The final team for each of those routes is unlocked after beating the story mode: Royal Academy for the regional qualifiers, Zeus Academy for the national competition. After beating each of those teams, you're given a rank based on the goal difference you obtained: "S" rank for 5 or more goals, "A" rank for 4 goals and "B" rank for everything else. Beating a team let's you challenge the next one and at the end of each route there's a chest containing two rewards: one for clearing the route, another for clearing the route with an "S" rank on every match. The "S" Rank rewards are manuals for a powerful shot and keeper skill unavailable elsewhere in the game.