fall inside a hole
Thomas the Tank Engine Doki Doki Mountain Set (2007)
First written May 10, 2025
The Plarail Thomas the Tank Engine Doki Doki Mountain Set (プラレールきかんしゃトーマスどきどきマウンテンセット) is a Thomas-series Plarail set released on July 19, 2007 that features a surprised-face Thomas and two trucks climbing up a large mountain and then sliding down a steep decline. The "Doki Doki" in the title is a reference to the sound of a heart pumping or pounding, referencing the adrenaline one might feel when going down the steep mountain.
This was the last box to use the mid 2000s darker blue stripe box style, with future sets (including the Toys R Us exclusive version of the set with a turntable and sidings) releasing in a lighter blue packaging style until 2012 when the range was updated to match the CGI look of the television series This particular copy has an ST mark of 12 signifying it was printed in 2012 and seems to have coexisted into the redesigned CGI-era packaging until it was rereleased in a new box with slightly different contents in 2014 under the same name.
Set contents| Quantity |
Item |
Photo |
|---|---|---|
| 3 pieces | Thomas with surprised face and two Troublesome Trucks |
 |
| 4 | R-01 Straight Rail |
 |
| 5 | R-02 Half Straight Rail |
 |
| 16 | R-03 Curve Rail |
 |
| 5 pieces | Mountain |
 |
This set comes with a surprised-face Thomas looking down towards the rail and the large drop ahead of him.
These Thomases are similar to the earlier Japanese release of Jet Engine Thomas and continued to be produced for many years, including through the point where the grey running board paint was changed to a lighter bluish color.
Thomas is hauling two Troublesome Trucks, a grey shocked face truck and a red happy face.
The red truck in this set (right) is very similar to one of the trucks included in the Thomas and Busy Freight Cars Set (left) and Thomas and Lots of Freight Cars Set but it seems perhaps a bit more vibrant. This could just be differences in production over time...
The large "Doki Doki" or Rollercoaster Mountain piece is made up of the main large base with spiral track and runnel and three sloped track sections that make up the dip. The last track section includes an arresting mechanism that will help slow Thomas down at the end of his descent. A castle is also included to sit on top - the international versions of the mountain include a flag that fits in on top, and the later Japanese release flattens out the top and replaces it with a sticker...
The large mountain base has a curved tunnel going through it with the track spiraling upwards. The height of the mountain is two and a quarter bridge girders tall and the brickwork has a cutout that can be used to attach bridges, with the Rattling Bridge Set later advertising its cross-compatibility.
The entire set is pretty large to fit around the big mountain base, and Thomas cycles around and races down the slope.
The speed arrestor at the bottom of the hill can sometimes catch Thomas or another engine up, especially if the traction tires are a little worn out. Heavier trains will also get pushed further down the slope.
Thomas in Roller Coaster Mountain Set (2007)
In 2007 Tomy Asia adapted the Doki Doki Mountain set slightly and released it in Australia and other Asian markets as the 789123 Thomas in Roller Coaster Mountain Set.
Set Contents| Quantity | Item | Photo |
|---|---|---|
| 3 pieces | Thomas with surprised face and two Troublesome Trucks |
|
| 4 | R-01 Straight Rail |
|
| 5 | R-02 Half Straight Rail |
|
| 16 | R-03 Curve Rail |
|
| 6 pieces | Roller Coaster Mountain |
Like other Asian market sets, the box for this release is based on the Plarail version and includes the Plarail-style Thomas with white running board.
The set includes the original export style of Roller Coaster Mountain with blue spiral track and flag. Otherwise, it is almost the same as the Japanese release.
| Set name | Plarail Thomas the Tank Engine Doki
Doki Mountain Set プラレールきかんしゃトーマスどきどきマウンテンセット Thomas in Roller Coaster Mountain Set |
Release period | 2007-2014, Japan 2007, Australia and Asia |
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| Notes: |
Thomas the Tank Engine Doki Doki Mountain Set (2014)
In 2014 the Japanese Doki Doki Mountain Set was rereleased in the new CGI style of packaging with slightly different contents. In 2018 the revised version of the set was rereleased in the updated darker blue packaging.
Set Contents| Quantity | Item | Photo |
|---|---|---|
| 2 pieces | Thomas with surprised face and red log car | |
| 3 | R-01 Straight Rail |
|
| 5 | R-02 Half Straight Rail |
|
| 16 | R-03 Curve Rail |
|
| 1 | R-08 Stop Rail | |
| 5 pieces | Doki Doki Mountain | |
| 3 | Logs |
These sets include the same surprised-face Thomas as previous sets but now has a red log car and three logs which go flying as Thomas comes down the mountain, which is a neat new element to the set.
The mountain was redesigned to have a flat top with a sticker of Harold the Helicopter. The rail layout now includes a stop rail.
| Set name | Plarail Thomas the Tank Engine Doki
Doki Mountain Set プラレールきかんしゃトーマスどきどきマウンテンセット |
Release period | 2014-2018 (first CGI box) 2018-2021 (second CGI box) |
| Vehicle rating |
| Track rating |
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| Accessory rating |
| Overall |
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| Notes: | Some parts are a little better and others are a little worse... |
In 2021 a new "DX" version of the Doki Doki Mountain set was released with a flatter mountain and smaller rail layout. The original 2021 release included a red troublesome truck with barrel loads in addition to the orange log car with logs solely included with the 2022 rerelease. The Thomas in these sets has a CGI-style surprised face and stickers on the sides showing rocks flying past Thomas.