Here's the original post I made on getting an all-weathers fixed gear for Japan. In the end, I brought mine back from Canada to Japan this summer. It's a modified '09 Kona Paddywagon. This is what it looks like in real life.
The following post is an updated version of the posting at the first link.
The 2009 Kona Paddy Wagon I am mostly happy with, but that's because I'd already experimented fixed gear on what's become my 'retro-cross', so I knew what I wanted. I compromised on my ideal, because I got this bike 25% off. I love fixed for the interval training it forces upon me, for the quick acceleration, and the low maintenance. I run both brakes. I am not a hipster: this bike is set up for real-world commuting, and bad weather riding on imperfect urban asphalt.
What I did to it was put a riser stem at the front, as I wanted my bars just below the saddle, not at my knees. I changed it from fixed/free to fixed/fixed, because I didn't need the free and the two-teeth bigger freewheel seemed as much work to push as the smaller cog, without the flywheel advantage of fixed gear. It is presently with 32mm tires, a 44 chainring and 16 and 18 teeth cogs: 74" and 66". Put a Brooks B17N on, shellacked cotton tape on the bars, which have been replaced for more regular road bars. Lost the chainguard. Have two-sided spd pedals. To have lots of room for the 32mm tires I chopped a pair of Planet Bike fenders* in half, fabricated some hardware, and attached them to the bike on Sheldon Fender Nuts. Love those.
I brought it here, rather than buy one here, because I'll use it here for a year and then sell it. I'll buy something more optimal when I go home. It really has too much toe-overlap, and not enough fender clearance. Were I to buy one in Japan, the only bike available in my size with the right geometry for a fendered fixie is the All City Nature Boy. I might get that when I go home, unless I come across something better. There is always the semi-disposable 'Windsor Timeline' from BikesDirect.
Tokyo's issue is relentless prevailing winds along the riverside bike paths, so I need two different fixed gear ratios for down and up-wind: the 74" and 66". I could set up a Sturmey-Archer S3X, though it has a lot of lash, with a 44t chainring and 15t cog: 80", 60" and 50". With 44t and 46t chainrings, a 17/20t Surly Dingle Cog, and an 18t freewheel, I'd get the following: 73 and 59" fixed without flipping the wheel, and 66 or 69" free, depending on how chain-line works out. We'll see. A lot of trouble for dubious benefit.
As for the baggage, I don't carry $#!+ on my back. The tool kit is under the saddle, and a simpler version of this: I have a Park Tool Fixed Gear Tool in the frame bag. That bag will also hold a shell, or another water bottle, wallet, keys, cell... It's a nothing rack on the front, but it holds part of the fender, weighs nothing, attaches without hardware, and let's me throw a bag on when I need to. Uncool? Whatever. I leave shoes and toiletries at school, but I can take a change of clothes back and forth on the front. Ideal. If I got really stuck, I could lash a bag to my Viva Saddle Bag Loop.
Lights? Same as on my randonneur-hack: a Planet Bike Sport Spot on the handlebar, a Planet Bike Superflash on one seat-stay, and/or a Planet Bike Superflash Turbo on the other seat-stay. Such visibility is not as direly necessary in Tokyo as Toronto, but it can't hurt. And yes, I do use the GPS mentioned in this link, which is uncool for a fixie, but you try not to get lost in Tokyo! More commentary on bottles and cages here: this bike has an Arundel Stainless, which I like well enough.
*Make sure to bend any protruding hardware on front fenders downwards. Toe-overlap on these bikes is bad enough without fender-stays catching on your footwear and bringing you down in an intersection. Didn't get run over, but it still hurt.