Complex sentence: Idate then tells the group about how Aoi tricked him three years ago into leaving Konoha, afterwards, Naruto decides to carry Idate for the rest of the race.
Split into simpler sentences: Idate then tells the group about how Aoi tricked him three years ago, forcing him to leave Konoha. Afterwards, Naruto decides to carry Idate for the rest of the race.