Tokyo's LaQua (Tokyo Dome City) Amusement Park: It has a coaster.
Located in the same complex as the Tokyo Dome, LaQua is an entertainment area and shopping center right in the middle of the city.
Once you get off the street and inside the "park" itself, it's a fun, nicely landscaped area with several rides.
The park used to have several coasters, but the only one remaining today is Thunder Dolphin. It was really good! I went on a Monday in early January and crowds were quite light. Unfortunately, the coaster closed within an hour or so of my arrival due to high winds, but I was able to get about five rides in before that time.
The park has a large Ferris wheel in addition to several other rides, many of which are indoors.
Located in the basement of one of the buildings, there's a Spider-Man style ride through Tokyo.
Your vehicle is supposed to take you to Akihabara or some other random part of Japan (Hakone tour, anyone?) but it gets hijacked or something like that, and you fly recklessly through the town. It's pretty fun.
The land that currently includes LaQua and Tokyo Dome has had an amusement park and baseball stadium for decades; Korakuen Stadium was formerly on the site of Tokyo Dome, and the old amusement park was where Parachuteland is now. That portion of the park is "upstairs" and holds a few small rides.
There's a little spinny ride, as seen above, plus a classic parachute ride. This, too, was closed due to winds (to the park's credit it was pretty windy, though I'm sure the coaster could have probably ran fine), but I've seen it operating and this one's passengers are standing; the only other one I've seen was the Great Gasp at Six Flags Over Georgia, and that had seats.
Parachuteland has a small shrine, a little statue located off a small path.
I took a ride on the Ferris wheel, the one ride at almost every park that never seems to close. SkyTree is quite visible standing high above its surrounding buildings.
There's Tokyo Dome. It was difficult to get a photo due to the sun shining directly into the cabin; the windows are very scratchy which makes taking a clear photo absolutely impossible. I've had to clean up all of these photos.
Here is another view of Thunder Dolphin, with its first drop. All of the coasters at the park were closed for over two years and as I mentioned before, the others have been removed. I thought this, too, would remain closed and possibly be moved to another park or scrapped.
It weaves around behind the mall before going through a hole in the building.
From there it's a long drop back down and some additional drops, turns, and a purposefully wobbly portion of track that I thought was quite fun. The park also has a shooting dark ride and other rides that are designed for children or the whole family. Coaster fans will head to the park for Thunder Dolphin, and families in the area can certainly enjoy the park. It's a good place to make a full afternoon and night - lunch at one of the restaurants or cafes, rides in the afternoon, and a Yomiuri Giants baseball game in the evening. But for those looking for a full day of fun at an amusement park, Toshimaen and Hanayashiki might be better options.
The attractions are open 10:00 to 21:00, and admission to the park is free. However, rides have charges, and a day pass is 3800 yen. Several lines access LaQua and the Tokyo Dome: JR Sobu-Chuo and Mita subway lines: Suidobashi Station; Marunouchi and Namboku subway lines: Korakuen Station; Oedo Line: Kasuga Station.