if you are going to Tokyo, i think a twiggy will be big enough of what you need to tote around.
and somehow i think the twiggy is a bit more casual than the city, so it should suit your holiday clothesss
I was going to say City until I saw the colour options... now, I would suggest taking the Officier Twiggy... Officier is gorgeous and will go with most outfits! And, as meganka said, it'll be enough for wandering around Tokyo - not too cold at this time of the year, too, so you'll only need a light wrap which can fit in the Twiggy. Have a good holiday!
I'd bring both - to have options, and also for the fact that you might bring more or less , depending on what you're doing in the day. Tokyo's a lovely place and people dress up, so it's nice to have more than one bag as an accessory! Have a lovely trip!
I'd go for the Twiggy. I brought my Anthra Twiggy to France last year. It holds pretty much the same as a City, and of course Bbags are so lightweight. I carried it everywhere with me - except the beach of course! I think Twiggy is less 'briefcasey-looking' for casual situations.
I think either would be gorgeous but agree that the twiggy is a bit more versatile, more casual less brief-case like but also can be dressed up for nights out. But that's just my personal preference. Take whichever one is easier for you to carry. (BTW, I occasionally wear the twiggy cross body, I find that the city that way looks odd on me but the twiggy is OK.)