I'm in the midst of getting my Japanese citizenship, though not my 'origin', Japan is more of a home to me than SG has ever been. So I'll chime in.
I miss the 4 seasons.
I miss the sun setting at 5pm when it isn't summer.
I sort of miss the sun raising at 3.30am when it is summer.
I miss the food.
I miss the service.
I miss the language, the bad tv, the wonderful, whacky commercials.
I miss seeing a guy dressed up as Pikachu, or Kamen Rider, appearing unannounced at the local mall.
I miss watching kids playing baseball at the nearby primary school from my balconey.
I miss driving in the mountains.
I miss driving among the fields of rice.
I miss standing at the top of mountains, spending hours doing nothing but looking out into the nightscape.
I miss having dinner on my balconey while watching the sun set in the distance.
I miss the nice women.
Dammit I feel like crying.