Voyage

Mr. Popo sends Goku back in time to train more. In the past he meets the young Master Roshi and his rival, the young Crane Hermit. Goku learns from their master Mutaito how to harness his spirit energy. During an incident where the Crane Hermit steals Roshi's love interest, Goku gets angry and manages to use his spirit energy successfully. Back in the present, Tien contemplates visiting Korin's Tower in order to train as Goku once had. (Source: Wikipedia)