When you approach the rice fields Lefty will talk to you. He will force you to distribute water for him.
Go to the Rice Lord and collect the water. As he himself states, there are about two dozen workers but only 12 bottles of Water. While distributing the Water you can learn what sort of man the Rice Lord is, and also here the tale of Horatio the Peasant. If you give out at least one bottle of water, Lefty will be satisfied. If you give out all 12 and then talk to Lefty or the Rice Lord you'll get 100 EXP.
This task, however, is a daily one; every day Lefty will expect you to show up and hand out water. To make him stop pressuring you just beat him up. This is easier said than done, however, as the Rice Lord and his cronies will pounce on you. You can shoot him from a distance if you like (unlike most NPCs he cannot be killed by bolts or arrows) or just drop your Ore before attacking (so the one who knocks you down can't steal any) and then repeatedly attack him until he finally goes down. If you abuse the programming oversight described above you can even get the Rice Lord to help restore your health.
Note that after Lefty attacks you, you can force him to switch to his bow by quickly jumping away several times. You can also hide behind the earthen walls for a pause. For an easy fight, try making him switch to his bow, then attack suddenly from behind an earthen wall with a melee weapon. Timed right, he won't have time to switch back to his mace.
When Lefty gets up, confront him. Tell him he can deliver the Water himself from now on. He'll agree, and you get 200 EXP. After this he will act significantly humbler whenever you talk to him. You can even tell him you want to beat him up again.