Nakomi's Manor is located in the past, left of the haunted forest. To get there you will need the flying machine first, which you will get at some point in your adventure and i'm not going to spoil it. Note: Only in the second time you get the flying machine, after the "anomaly".

After getting to the place shown in the picture, you will notice how the place loops itself around, and the only sign reads "up a down b", to surpass this "obstacle" you need to input the so famous "konami code", basically a code that's been used as a cheat in many konami games and is now a joke used as reference in many places. To input it, easy, just go the folowing way: up, up, down, down, left, right, left, right, down, up. Note: The two last inputs were suposed to be "b" and "a", but as the sign indicates, their equivalents are "down" and "up". And voilá! You got yourself... a star, well that's a shame, but anyway, congrats.