At the beginning of Stage 5, Isa and Kachi find that they've teleported out to a desert road, far from their destination of Mt. Fuji. Kachi manages to find a pack mule, or "space donkey" as Isa calls it, but Isa still needs a ride. What does Isa do? He finds a Mook on duty, ambushes him and strafes the mook's gunfire, before kicking the poor sap out of commission and stealing his air bike.
In Stage 6, punching out Deko in hand-to-hand combat
At the beginning of Stage 7, Isa's transformation, and Isa vowing to defend Kachi's heart for the very final part.