S04E74: The World Ten Years Later

Reborn is hit by Lambo's ten year bazooka and sent to the future. The strange thing is nobody came in his place. Thus Tsunayoshi Sawada tries to make Adult Lambo appear by taking Lambo's bazooka and firing it at him in order to explain what had happened, but results Tsuna to be accidentally shot in the process. He then appears in the world ten years in the future. Hayato Gokudera also appears and soon realise they are not being sent back after the usual time limit. They are then attacked by Lal Milch who is later revealed to be an ally. English