there is no future tense. Future is same as present, so meaning depends on context.

asu　wa　ame　ni　naru de shou あすは　あめに　なる　でしょう 明日は　雨に　なる　でしょう It will rain tomorrow. なるでしょう＝will

If you want to say "Tomorrow I will...." You just use the plain plain form of the verb Tomorrow I will go to eat 明日私は食べに行きます。（Or more simply 明日食べに行く）

There is no future tense in Japanese.