When I was learning Japanese in school, I learned that you can mark the objects of the three verbs kuru (to come), iku (to go), or kaeru (to return) by using the particle e.  For example, if you want to say I will go to Tokyo, you can use the sentence: [Watashi wa] Tokyo e iku.

When I came to Japan, I discovered that instead of using the particle e, you can also use the particle ni. So you can convert our previous sample sentence to [Watashi wa] Tokyo ni iku.

You may be wondering whether there is a difference in using the two particles.  Aside from the spelling, there is in fact a difference in nuances. To be precise, the particle ni indicates the target or destination while e indicates direction.  This means that using ni is more specific than using e.

In other words, when you say Tokyo ni iku, you are implying that it is not Hiroshima nor any other city, but specifically Tokyo where you will go to.  On the other hand, saying Tokyo e iku would mean you will go towards the direction of Tokyo, not necessarily limiting to the area where Tokyo is located.  

In Tagalog, we can perhaps translate it as in the following:

Saan ka pupunta?
1) Sa Tokyo. (Tokyo ni iku.)
2) Pa-Tokyo [ako]. (Tokyo e iku.)