As you may already know, Japanese does not have a future tense, so when you want to say something like “I will go to Tokyo tomorrow”, you have to indicate how likely the event is going to happen.

If it’s been decided and arranged already, you use “non-past” form:

あしたとうきょうにいきます。

If you aren’t sure but you think you will, you say:

あしたとうきょうにいくでしょう。

If you are less sure about that happening:

あしたとうきょうにいくかもしれません。

(This is more like “I may go to Tokyo tomorrow.”)

If you want to emphasise your intention, you can say:

あしたとうきょうにいくつもりです。