Without his powers Daisuke has several possibilities for his profession:
Car mechanic - Daisuke was always interested in machines
Cook - Preferably in a small Japanese restaurant. Again, it has something to do with Daisuke's interest
Archer - Daisuke had quite some knack for bows. So if he had pursued his hobby for longer he might become a national champion
Mercenary/Soldier - Daisuke isn't someone who would turn his head away when people are in danger. If there would be a great war, Daisuke would surely enlist as a soldier or otherwise find his way to the battlefield.
War relief aid transporter - On the same trail of thought Daisuke has a burning desire to help people in need. As such he would eagerly volunteer for jobs that could help the unfortunate victims of a war's aftermath. Same about the starving and the poor.