There isn't really "motor sports" specific model store, but I think you can find pretty much everything you need at Mr. Craft in Ebisu.
< Mr. Craft in Ebisu (JR Yamanote Line)>
Reference only.
Mr.Craft closed the business on Sep.8, 2008.
You take the JR Yamanote Line, and get off at the Ebisu station.
I couldn't find English / Chinese guide in the JR website, but I'm sure you can read the characters.
http://www.jreast.co.jp/estation/stations/290.html
Take the West Exit on the ground level (right hand side in the picture), and head to the "key" looking icon where paid lockers are located. You should be at the upper left corner just outside the Ebisu station in this google map.
http://maps.google.com/maps?f=q&hl=e...,0.010815&om=1
Go north, and cross the wide yellow street, and walk along the narrow white street. Mr. Craft is 2nd or 3rd building from the intersection. It shouldn't take no more than 1 minute from the station. The first floor is for import toys, but 2nd and up are for scale models. They also have care related books and DVDs.
Open daily.
Weekdays: 12:00 - 22:00
Sat.Sun.Hol. 11:00 - 22:00
< Auto Modeli GT in Ueno (JR Yamanote Line)>
Another place you might want to try is Auto Modeli GT, the producer of the Finisher's brand.
http://vfkfcgt.hp.infoseek.co.jp/
They recently relocated, so I haven't had a chance to visit their new store, but their lacquer paints are pretty good. (It's not that you can't find them at Mr. Craft and other places, but you know...)
It's near the Ueno station on the JR Yamanote Line.
http://maps.google.co.jp/maps?f=q&hl...03328,0.010815
This is a bit hard to navigate, but you might have a better chance following the wide yellow street until the 4th traffic light, and make a left turn.
Hours:
12:00 - 21:00 Closed on Tuesday
12:00 - 18:00 Friday
13:00 - 18:00 Sunday and Holidays
(Also check the calender on the website for irregular hours, like closing at 18:00 Mon and Fri this month [Jun08].)
< Auto Modeler's Cafe in Kotake Mukaihara (Metro Yurakucho Subway)>
Another new place that I haven't been is Auto Modeler's Cafe.
Some say that you get a 10% off on Studio 27 kits, so you might want to go there before Mr. Craft.
http://www.amc-models.com/index2.html
This one is really hard to navigate (partly because I haven't been there), but they have directions on their website, so I'll translate the captions for you.
http://www.amc-models.com/infomap.html
1) Use the Metro Yurakucho Subway Line and get to Kotake Mukaihara. Taking the exit 3, you'll see the sight like this picture. Head to the convenience store "Sunkus."
2) After passing the Sunkus store, head to the sign board saying "木下箔押所."
3) There are guard pipes like this on the sidewalk. You jump over each one of them.
4) After passing the 木下箔押所, you'll see this mysterious blue pillar. Turn left here.
5) Another picture of the blue pillar, taken from the street.
6) After turning left at the blue-pillar intersection, you'll see a steep slope like this, which I call Mukaihara Eau Rouge.
7) Looking up from the bottom of the slope. You're almost there.
8) At the top of the slope, turn left and you'll see the AMC store.
<* The remaining 4 pictures are driving directions>
The store hours are:
13:00-20:00 (Open till 21:00 on Fri and Sat)
Tue, Wed: Closed
You might want to check this Wiki article on the Yurakucho Line.
http://en.wikipedia.org/wiki/Tokyo_Metro_Yurakucho_Line
< Yellow Submarine in Akihabara (JR Yamanote or Sobu Lines) >
Unfortunately, the Yellow Submarine Shinjuku branch closed, leaving me no choice but to only recommend the one in Akihabara. It isn't so big on scale models, but sometimes you can find pre-owned kits and also some kit parts sold separately.
It's located on the 7th floor of the Radio Kaikan building.
http://maps.google.co.jp/maps?f=q&hl...,0.010815&om=1
I don't think I have to explain how to get to Akihabara, because pretty much all Tokyo guide books should have it.
You exit the station to the electric town side of the station, and the Radio Kaikan is across the street. The building looks like this from the station.
http://maps.google.co.jp/maps?f=q&hl...2.46,,0,-15.37
It has many hobby stores, selling all kinds of stuff from toys and dolls to obscene anime/manga stuff. The whole experience in Akihabara is pretty fun if you haven't been there.
Yellow Submarine Akihabara branch is open daily between 11:00 - 20:00
Explore the Radio Kaikan building because it houses many hobby stores besides Yellow Submarine. (Also the floor arrangement gets changed every now and then, so my info might not be up-to-date.)
< Yodobashi-Akiba @ Akihabara on JR Yamanote or Sobu Lines>
In addition, if you are going to hit Akihabara, you might want to visit Yodobashi Camera Akihabara branch (Yodobashi-Akiba for short) as your first stop, because it's supposed to offer hefty discount (like 30%). (Apparently, the store has a Foreign Exchange booth on the ground floor.) Toys and models should be on the 6th floor. Unlike specialty shops, however, Yodobashi is a department store, so the selection might be limited, and most of the stuff are probably only new releases. It's on the other side of the station from Yellow Submarine.
http://maps.google.co.jp/maps?f=q&so...38,0.0103&z=18
< Tokyu Hands @ Shibuya on JR Yamanote Lines or some subways>
Another cool place is Tokyu Hands in Shibuya.
This is a multi-level DIY specialty store which has all kinds of crafting tools and materials. It's worth a visit if you have extra time.
The easiest way to get there that I can think of is to find this intersection first.
http://maps.google.co.jp/maps?f=q&so...286.89,,0,1.06
Then take this mild slope up to a Y intersection (where you see the gray police booth to your left), and follow the yellow path in the Google street view.
http://maps.google.co.jp/maps?f=q&so...331.14,,0,-0.2
You'll eventually find the sign to your right.
http://maps.google.co.jp/maps?f=q&so...9.68,,0,-21.67
Store hours are 10:00 - 20:30.
Shibuya station is one of the largest train hubs, so any guide book should have it. Tokyu Hands is about 15 minutes from the station, and you get to cross possibly the world's busiest crosswalk.
http://www.youtube.com/watch?v=QXtOd...eature=related
Have a good English travel guide to Tokyo, and cross-reference it with the linked maps, because you'll still have to navigate yourself to each of the nearest train station, and I know that Tokyo is totally unfriendly to visitors (even to the Japanese who don't work or live there).
Also, don't bother using credit cards, because 1) Japanese people hardly use it at retain stores or restaurants, and 2) foreign credit cards usually don't work immediately. I rarely see anyone who's managed to use a foreign card without the pain of manual authorization by having the store manager call the regional headquarters, and it takes a lot longer than you'd expect. You might be okay with a little wait, but that's not how the society works, because you're not supposed to incontinence others around you regardless.
Get a plenty of cash at the airport, and save the trouble. The only exceptions I can think of are the hotel and large retail chains (like Yodobashi Camera) because they are used to visitors from overseas.
Also, expect a lot of walking, so a good pair comfortable shoes is a must.
I hope this helps. Have a safe trip.