How do you get power berries in harvest moon ds?

There are no power berries in this game. There is only your stamina and fatigue levels that are at a fixed rate. Your maximum stamina rate is 100. Once your stamina hits 0, your fatigue starts to count up. Once your fatigue hits 100, you pass out. The only way to chance this it to buy the harvest goddess and kappa items. They decrease your energy use, help you gain back your energy, and can temporarally increase your maximum stamina and fatigue levels. You buy these form Van and the Harvest Sprite Company Tree.