Katekyo Hitman Reborn!

Tsuna and his friends split up and explore the Namimori of the future. They all coincidentally meet in front of their school, Namimori Middle, and relax in their classroom. Tsuna realizes that to return to their own time, they must defeat Byakuran in the battle of choice. On the roof of Namimori Middle, Hibari encounters the future Dino who insists on training him.