Showa Kinen Park Guide: The Future of Tachikawa’s Unfinished Park

Showa Kinen Park, open 42 years, is still 6% unbuilt. Why nobody bid for the old Rainbow Pool site, and what the park plans to become by 2030.

日本語で読む（Japanese version）

Showa Kinen Park (国営昭和記念公園, the Showa Memorial National Government Park) is not finished yet. Forty-two years after it opened, a park that 3.8 million people walk through each year is, on the national government’s paperwork, still under construction.

Say that to someone from Tachikawa (立川) and they will probably laugh. There is that huge open field, the tulips bloom, the ginkgo trees turn yellow, there are even fireworks. What, they will ask, is unfinished about it? But the documents of the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) say it plainly. Of the planned area, 94% is open. The remaining 6% is scheduled to open in fiscal 2030. (Japan’s fiscal year runs from April to the following March.)

In the middle of that 6% lie the remains of the Rainbow Pool, which once single-handedly took care of summer in Tachikawa. The national government sought private businesses to rebuild the site with private-sector money. Not a single one put its hand up.

This is the most conspicuous corner of one of Japan’s leading national government parks. Why did nobody come? And what is this park trying to become? Using only publicly available government documents as my guide, I set out to follow the park’s future.

The future of Showa Kinen Park: 42 years old and still 94% open

Showa Kinen Park goes back to a Cabinet decision of 30 November 1979. As a project to commemorate the fiftieth year of Emperor Showa’s reign, a national government park of about 200 hectares would be placed on the site of the US military’s Tachikawa base, which straddled the cities of Tachikawa and Akishima. That is what the wording of the Cabinet decision lays down. (Showa is the reign name of the emperor known abroad as Hirohito, and of the era from 1926 to 1989.)

Here the first surprising number appears. The planned area used for the park today is about 180 hectares, not 200. According to the project evaluation documents of MLIT’s Kanto Regional Development Bureau, development has so far gone ahead with 180 hectares as the planned area, in view of the situation of the reserved land. The area decided by the Cabinet and the area actually being built have been 20 hectares apart from the start. Those 20 hectares come to roughly four Tokyo Domes, the baseball stadium that Japanese people use as a unit of size.

On 26 October 1983 the first phase opened, 70 hectares including Minna-no-Harappa, the Open Field. After that the park spread little by little, like tree rings: the Waterfowl Lake, the Children’s Forest, the Japanese Garden, the Bonsai Garden, Komorebi-no-Sato (a recreated farming hamlet) and the Flower Hill. The last big opening was on 1 April 2014, the second-phase area of the Green Culture Zone. On that day the open area reached 169.4 hectares, and the number has not moved since.

The national government’s project outline for fiscal 2026 gives the planned area as about 181.3 hectares and the area in use as about 169.4 hectares. On the opening map, the “not yet open area” outlined in blue remains at the western end of the park, on the Akishima side. It is exactly where the remains of the pool are, and the land returned from a Tokyo Metropolitan flood-control reservoir.

Being unfinished also means it still has a budget. According to the project evaluation documents, the park’s total project cost is about 71 billion yen, up 6 billion from the 65 billion of the previous evaluation. The project period has also been extended by six years, and full opening is now scheduled for fiscal 2030. The government measures whether the park pays off with a yardstick called the cost-benefit ratio, and the value is 1.7: for every 1 of cost, 1.7 of benefit. The period covered by the calculation is the 97 years from fiscal 1983 to fiscal 2079.

2079. The government intends to keep the books until today’s mud-covered children bring their grandchildren to the field. A park is a patient business.

The fiscal 2026 budget breakdown also shows the park’s age. Development costs are about 680 million yen, while maintenance and management costs are about 1.3 billion yen. Nearly twice as much goes on keeping what exists as on building anything new. As with people, once a park passes 40, keeping in shape takes more effort than growing.

The way it is kept has a little-known mechanism too. According to the materials from a briefing session, the park’s management and operation is contracted out by the state to private operators, and from fiscal 2022 to 2026 it is handled by a consortium including the Parks and Recreation Foundation (Koen Zaidan), a general incorporated foundation. The materials go out of their way to note that this is different from the “designated manager” system often heard of in local-government parks. The admission fee we pay at the gate is not the operator’s revenue; it goes into the national treasury. The few hundred yen paid at the entrance to the field take a long way round into the national purse.

“Restoring greenery”: the base trees that survived

The park’s theme has not changed since the project began: “Restoring greenery and enhancing humanity”. Bringing green back to the site of an airfield.

The way it was restored was more careful than I had imagined. According to the materials from a briefing session the park office held for private businesses in April 2026, about 19,000 trees were growing on the former base site before the park was built. Of these, about 6,000 were saved, either left where they stood or transplanted. The great zelkova on Minna-no-Harappa is one of them. Rows of ginkgo, horse chestnut and cherry trees were also worked into the plan so as to keep their original shape. On top of that, a coppice wood was created with about 10,000 trees planted by citizens.

I had vaguely assumed it was a park planted from scratch on a base. Wrong. Roughly one in three of the trees that had lived through the base era was kept alive as a park tree. Trees that grew up beside the roar of aircraft now see in the fireworks nights.

So who is walking through this unfinished park now? The numbers tell of an unexpected change.

3.8 million a year, 100 million in total: visitors in numbers

Back then, from the opening to the end of the Heisei era (1989–2019), Showa Kinen Park was a park that welcomed about 4 million people a year. From fiscal 2014, five years in a row of 4 million. In fiscal 2020, with the COVID-19 pandemic, it fell to about 1.79 million, but by fiscal 2025 it had recovered to about 3.8 million. And on 8 April 2022, the total number of visitors since opening passed 100 million.

A hundred million. A number close to Japan’s population has passed through the gates of this field. Of course, the same people come many times, but it is a lot all the same.

Now the make-up of those numbers is starting to change. Reading the briefing materials, in fiscal 2025 visitor numbers for April, November and January were the highest on record. November even set a new record for a single month. The night illumination called “Autumn Night Walk” drew about 330,000 people into the park after dark over its 30 days. At the summer fireworks festival, about 350,000 people looked up at the sky inside the park alone.

Spring flowers, autumn leaves, winter nights. Visitors surge in great waves season by season. According to the materials, the Flower Festival from March to May drew about 1.26 million, and the autumn leaves festival in November about 530,000.

Big waves hit the shore. The materials do not hide the park’s troubles. In fiscal 2024, the car parks were mostly full on weekends and holidays in the busy seasons; on 6 days every car park was full, and on 30 days the Nishi-Tachikawa Gate car park alone. The entrances are lopsided too. Of the paid gates, the two at Tachikawa Gate and Nishi-Tachikawa Gate take more than 80% of visitors, while only 3% enter through Akishima Gate. On spring and autumn weekends, the park’s capacity to host events is almost at its limit.

A 180-hectare park, and people are jammed at the gates. It is like living in a huge house where everyone takes off their shoes in the same small entrance hall.

The other change is the heat. The materials include a graph, made from Japan Meteorological Agency data, of the number of “extremely hot days” (35°C or above), and say they tended to increase from 2019 to 2025. Walking 180 hectares at midday in high summer is now close to an adventure. So the park has started looking to the night. In summer it held a night opening called “Starry Sky Walk”, shifting opening hours to 12:30–21:00, with the great zelkova lit up, hand-held fireworks and star-watching sessions.

The park of those days was a daytime park, opening in the morning and closing in the evening. The park of today has started welcoming people at night too. And the park of the future is missing one more, decisive, thing. Its summer star.

Why did nobody bid for the Rainbow Pool site?

The Rainbow Pool, the symbol of summer, closed after its fiscal 2019 season, and demolition and removal are now under way. I wrote about the pool’s history, and how the government sought operators through “Park-PFI”, which borrows private-sector strength, in the summer instalment of this series. Here I will repeat only the ending. In the call for bids from 25 March to 16 June 2025, not a single business expressed an intention to take part.

Park-PFI is a scheme in which a private business builds and runs income-earning facilities such as cafés and play areas inside a park, and in return uses its earnings to improve the surrounding paths and open spaces. The private business gets its permit extended from the usual maximum of 10 years to 20 years. The state’s budget burden gets lighter. If it works, both sides gain.

So why did nobody come?

On 21 April 2026 the park office held an on-site briefing for private businesses and published the materials and the Q&A. In them is the government’s own reflection. Reading it surprised me a little, because for an official document it was remarkably frank.

The materials give three main reasons for the call being cancelled.

The first is the price of things. Shortages and rising prices of raw materials and energy, and the weak yen, pushed up the cost of materials, and there may have been a gap between the government’s estimates and actual prices. A labour shortage across the construction industry also made it hard to secure a building team.

The second is the nature of the land. For the site of the flood-control reservoir, the materials say, operations that keep down noise and light are needed in order to protect rare birds of prey. Please gather crowds on a big open space and make money, but quietly, and in the dark. A difficult order. There are birds that need quiet in a place you can reach by train from central Tokyo. That in itself is something this park can be proud of.

The third goes deepest. The government’s and the private sector’s “pictures of the future” did not match. In the previous call, the government showed only the concept of the area and left the contents to private proposals. The idea was to let them think freely. But from the private side, it was impossible to see what functions and scale the government expected, so it was hard to decide the direction of a proposal. According to a diagram in the materials, the government pictured “income-earning facilities occupying most of the area, with open spaces just supplementing them”. The private sector pictured “income-earning facilities in only part of the area, with open spaces at the centre”.

One side was imagining “a park with lots of shops”, the other “a park with few shops”. No wonder the numbers did not add up. It was like a first date at which one person assumed they would live together and the other assumed they would live apart.

The Q&A gets concrete about money too. In the previous call, the government was to pay about 2.5 billion yen of the cost of open spaces and the like, on condition that its share was 80% or less. And the private side was expected to build almost all of the park facilities, including the gate building and the water-play facilities.

The previous plan had its dreams, too. The project evaluation documents show two photographs as models. As an example for a new Akishima Gate, the entrance of the Singapore Zoo, which makes use of greenery while opening out to its surroundings. As an example for new water-play facilities, the waterside of Parc André Citroën in Paris. A Singapore gate and Parisian fountains side by side at the western end of Tachikawa. As a picture, rather grand.

The result, zero expressions of interest, is unglamorous but weighty. The seat of the summer star stayed empty, and another summer went by.

But the government has started a rebuild so as not to repeat the same failure. Look at what it contains, and the park’s future begins, little by little, to take shape.