If no monster is in Tokyo, you must enter and place your Monster in Tokyo City. Doing so gains you 1 Victory Point .
With five (5) or six (6) players, if Tokyo is occupied, but Tokyo Bay is empty, you must enter Tokyo Bay. Monsters in Tokyo City and Tokyo Bay are both considered to be "in Tokyo". Tokyo Bay has the same effects as Tokyo City.
If you survive a full round in Tokyo and are still there in the beginning of your next turn, you earn 2 Victory Points .