Tachikawa in Summer: Things to Do, Water Play and Heat Tips Guide

Showa Kinen Park’s Rainbow Pool closed after summer 2019. Where does Tachikawa cool off now? A misty forest, morning water lilies, and how to walk in the heat.

日本語で読む（Japanese version）

Summer in Tachikawa (立川)? The Rainbow Pool, plenty of people would say. Anyone who grew up in the Tama area — the western half of Tokyo, beyond the 23 central wards — may have a memory or two of walking from Nishi-Tachikawa Station to the park with a rubber ring under one arm. I, too, thought that if I were going to write about summer in Tachikawa, I would have to start with that pool.

But the first thing that came up when I began looking was a slightly cold phrase in a government press release: “the former Rainbow Pool site.” Former site. The giant pool, which at its peak was used by more than 300,000 people a year, has not been filled with water since the end of the 2019 season.

So where did Tachikawa’s summer go? While the pool sleeps, where do the children of this city touch water, and where do the adults ride out the heat? I decided to start my summer walk in Tachikawa at the former site.

Where to play in the water in Tachikawa in summer: the Rainbow Pool is closed

Let me give the answer first. As of 2026, the Rainbow Pool at Showa Kinen Park (Showa Memorial Park, a national government park) is not open. According to the Ministry of Land, Infrastructure, Transport and Tourism, it was loved as a symbol of summer from the time it came into use in fiscal 1985, but it was taken out of use after the fiscal 2019 season. The reason was age. The national government’s overview of the park’s work for fiscal 2026 says that demolition and removal of the ageing pool “will continue.”

There are other places in Tachikawa to meet water and coolness in summer. In the park’s Children’s Forest there is a “Forest of Mist,” where artificial mist rises on a timetable. Along the City of Tachikawa’s Negawa Greenway there is a waterside spot the city describes as “a water plaza where children can play safely.” On the park’s Waterfowl Lake you can take out a boat. And if the heat is getting the better of you, there are 231 “cool-off spots” (hitosuzumi spots) around the city.

The pool is asleep. But summer’s water is still scattered all over the city. This article is about gathering up that scattered summer.

First, let me start with the pool that is sleeping. When, where and how was it born?

28 June 1985: a rainbow pool opened on the site of an airfield

The official website of Showa Kinen Park has a timeline from its opening. On 26 October 1983, the first phase, 70 hectares, opened. The next line reads: 28 June 1985, “Rainbow Pool opens.” The open area grew to 82 hectares. Twelve hectares at once — about two and a half times the size of the Tokyo Dome — opened just before summer. The event recorded on the line after the park’s opening was the pool.

In the middle of the rainy season, just before the school summer holidays. The opening date alone makes the aim plain.

The park’s land was originally the US military’s Tachikawa Airfield. On that flat ground where runways and hangars had stood, first came a meadow, and two years later a giant water park with nine kinds of pools. Articles on a parenting website and a leisure booking site show that there were nine types of pool in all, including a lazy river, a big wave pool and water slides. On land where aircraft once took off and landed, children now came splashing down from slides into the water. As uses of land go, it makes a certain sense.

According to a 2024 article in the Tokyo Shimbun newspaper, the Rainbow Pool opened in 1985, the park’s third year, and at its peak was used by more than 300,000 people a year. I cannot quite picture 300,000 people. Tachikawa’s population is just over 180,000, so even if every resident swam once each summer, it would not be enough. The summers of all Tama — no, of all Tokyo — must have gathered at that pool.

This pool left a slightly comic legacy, too. The online encyclopedia Wikipedia, citing articles from the Asahi and Yomiuri newspapers of the time, tells this story. In 1995, during Japan’s “employment ice age,” when graduates struggled to find jobs, the park decided to cheer on female university students having a hard time job-hunting: it named 16 August “Female University Students’ Day” and invited them to the Rainbow Pool for free. The date was based on the belief that on 16 August 1913, Tohoku Imperial University had announced that women had passed its entrance examination.

That date then spread through the wider world. But according to Tohoku University, the first announcement in Japan that women had passed a university examination was made on 21 August. In 2020, Tohoku University applied to the Japan Anniversary Association to register 21 August as “Female University Students’ Day,” and it was officially registered. A date set by a pool promotion was corrected by a university 25 years later. The pool’s water had sent its ripples surprisingly far.

The park’s water play was not only the pool. The park’s official page on the Mountain Stream Plaza contains a surprising sentence. The Mountain Stream Plaza, now known as the spring tulip garden, was used when it opened in 1988 as a plaza where you could play in the water. The plaza is a waterside where a stream flows gently for about 700 metres along the west side of the park’s Minna no Harappa meadow. The official text scratches its own head: it feels strange, it says, to think of children in swimsuits playing in the stream that now flows between the tulips. The party writing the park’s history is the one most surprised.

Leaf through the City of Tachikawa’s timeline, and you find that Showa-era Tachikawa had other summer waters too. In 1962, an amusement park was completed in Suwa no Mori Park. In 1973, the Tamagawa Ryokuchi Park was completed, and the same year has the line “Mikagebashi Park Pool opens.” It was also the year the full return of the Tachikawa base was decided. A year in which a base town whose return had just been agreed opened a city pool.

Today, in the city’s list of sports facilities, the names listed under Mikagebashi Park are an athletics ground and a baseball field; there is no pool to be found. Suwa no Mori Park, too, is described by the city as part of the sacred grove that once surrounded the shrine, developed after the war into a modern public park — with no mention of an amusement park. Showa-era summer water survives only as single lines in a timeline.

Set side by side, it looks like this:

• Then (summer 1985): nine kinds of brand-new pools, which would later draw more than 300,000 people a year. In 1988, children in swimsuits waded into the Mountain Stream Plaza.
• Now (summer 2026): the pool is part way through demolition and removal. The Mountain Stream Plaza has become a spring tulip garden, and the children in swimsuits are in the mist of the Children’s Forest.

For those who remember the Showa era, the contrast brings back the smell of rubber rings and the sting of sunburn. For those born at the end of the Heisei era, the very fact that the park once had a giant pool is probably news.

Summer in Tachikawa used to be something you spent in a swimsuit. So how did it become a “former site”?

The word “former site,” and the summers of the 2030s

A 2023 project evaluation document from the Kanto Regional Development Bureau of the Ministry of Land, Infrastructure, Transport and Tourism includes photographs of the pool’s current state. The heading reads “Suspension of the pool due to ageing.” Next to one photo is the caption “Deterioration of a pool water inlet.” From 1985 to 2019, across 35 summers, this equipment circulated the water of hundreds of thousands of people. No wonder it was tired. The Tokyo Shimbun also wrote that user numbers had been falling in recent years and the equipment was ageing. The crowds and the pipes grew old at about the same time.

According to the same document, the parts of the park needing work were concentrated on the Akishima side. Besides the pool, a flood-control reservoir on the Zanbori River that Tokyo had been using was relocated, and about 2 hectares of land were returned to the national government at the end of fiscal 2018. At the park’s western edge, a cleared plot and the pool site sit side by side, waiting for their next role. When the park was first designed, the area around the Akishima entrance near the pool was “reserved” land among the returned base land, with no fixed use. So the Akishima Gate was treated as a secondary gate. But from 2018 onward, land readjustment moved ahead in the neighbouring Akishima district of the former Tachikawa base, and a Ministry of Justice facility, housing, a shopping centre and a waste incineration plant went up one after another. As a town has grown up around it, the park’s back door is gradually being handed the role of a front entrance. The redevelopment of the pool is part of that flow.

It is not that the park itself has lost its popularity. According to the national government’s overview for fiscal 2026, annual visitors were around 4 million a year before the pandemic, fell to about 1.79 million in fiscal 2020, and had recovered to about 3.8 million by fiscal 2025. The people have come back. Only the summer water to welcome them has not yet returned.

According to the Tokyo Shimbun, in March 2024 the park office published a draft redevelopment policy to demolish and remove the pool and create on its site a “waterside space” (shinsui kukan) where people can enjoy water all year round, and invited public comments.

Then, in March 2025, the national government began recruiting operators under Park-PFI, a scheme that borrows private money and ideas to build and run park facilities. The recruitment documents divide the area around the Akishima entrance into three zones and name one of them the “New Water Space Renewal Area,” planned to hold waterside facilities and a lakeside restaurant, with use targeted to begin during fiscal 2030. The other two are the “New Akishima Gate Area,” with a new gate building, a cycling centre and parking, and the “New Recreation Area,” with new play facilities and a barbecue garden. The operator was to run the facilities for 20 years after they opened (30 if extended), and then remove them and restore the site. A remarkably patient plan, looking ahead to summers 20 years away.

But things did not go so smoothly. When the deadline for expressions of interest closed on 16 June 2025, not a single one had been submitted. The park office’s web page states plainly that no expression-of-interest documents were submitted. Nobody put their hand up to rebuild the summer’s star attraction.

The national government has not given up. According to a March 2026 announcement, it has revised the conditions and is preparing to invite bids again at the end of fiscal 2026. In April it held an on-site briefing for private businesses, and the places to be inspected included the “current Akishima Gate” and the “former Rainbow Pool site.” The briefing notice lists 35 summers, quite casually, as one stop on the tour.

The national government’s fiscal 2026 overview explains that 42 years have passed since the park opened, that circumstances around the park have changed, including ageing facilities, and that this is why the redevelopment of the Akishima entrance area is under way. Thirty-five summers were the pool’s working life; 42 years is the park’s age.

When, and what kind of waterside will appear on the pool site, has not yet been decided. The only certainty right now is that it has not been decided.

So, in summers without the pool, where do Tachikawa’s children get splashed? One answer lies in a forest at the northern end of the park.

The Children’s Forest “Forest of Mist”: on the hour and half-hour, the woods turn white

The Children’s Forest (こどもの森, Kodomo no Mori) in Showa Kinen Park is a forest for children that opened in full on 9 October 1992. On the official website, the names of its play areas read like the contents page of a book of fairy tales: Moon Hill, Underground Spring, Forest Fort, Rainbow Hammock, Sky Slide, Pyramid of the Sun, Stone Valley, Dragon Sand Hill.

In summer, the one I am drawn to is the Forest of Mist (霧の森, Kiri no Mori). The official description goes like this: when pure white mist suddenly fills the air, you are in a fairy-tale world. The mist comes out from 10 a.m. to 3 p.m., for 15 minutes starting on the hour and at half past. When humidity is high, it runs for 5 minutes.

The mist appears on schedule. A forest’s mist with a timetable. The fairy-tale world is extremely punctual. Fifteen minutes in every thirty — which means that for exactly half the daytime, the forest is smoking white. A child sweating in the sun waits for the hour and dashes into the woods. A grown-up watches the clock and waits for the child’s back to vanish into the mist.

The descriptions of the other play areas are fun to read too. From the Pyramid of the Sun, if you climb its long stairs, you can see the Children’s Forest from end to end. Stone Valley is a gorge lined with big rocks that you can climb over and crawl under, but the official website addresses children directly: “Promise you will never, ever climb the stone wall under the ‘Valley Bridge,’ OK?” Dragon Sand Hill has four big dragons waiting with their mouths open — with a footnote that, because safety standards for play equipment have become stricter, you can no longer climb the dragons. The unclimbable dragons wait in the sand with only their mouths open. Even a monster beloved of children cannot defy the rules of the times.

The mist has its days off, too. From December to February, it is stopped to prevent freezing. Winter mist freezes. So the Forest of Mist is a forest for summer.

At Waku Waku Plaza, the entrance to the Children’s Forest, the official description says mist or fountains may suddenly greet you with a “Welcome!” The Underground Spring is a large bowl-shaped hollow like a meteorite crater, and at its bottom, it says, is a mysterious spring whose water level changes with the seasons.

In one corner of the forest hangs the Rainbow Hammock, which the official website describes as “the largest hammock in Japan.” It is for elementary school children and younger only. I wrote about it in the Showa Kinen Park story, so here I add just one thing. In 2026 there are days when it is closed all day for inspection, on set Wednesdays in May, July, September, November and January the following year. If you are planning a summer-holiday visit, avoid the second Wednesday of July. Even Japan’s number-one play equipment has its health check-up day.

For families, some practical notes. The play equipment in the Children’s Forest can be used from 9:30 a.m. until 30 minutes before the park closes. The white dome “Sea of Clouds” closes 45 minutes before the park and is for junior high school students and younger only. On some days it cannot be used from opening time because of morning dew or frost. In the forest there is an information building, Mori no Ie (the Forest House), with a first-aid room and a baby room, and staff are always on hand. Baby buggies can be borrowed free at each gate: according to the official website, 12 at the Tachikawa Gate, 15 at the Nishi-Tachikawa Gate and 8 at the Sunagawa Gate. It is first come, first served on the day, so on summer-holiday weekends, the early bird gets the buggy.

The Children’s Forest is in the northern part of the park. According to the official guide, it is about 35 minutes’ walk from the Tachikawa Gate, about 25 from the Nishi-Tachikawa Gate and about 23 from the Sunagawa Gate. Walk there from Tachikawa Station on a summer noon, and you may evaporate before you reach the mist. Taking the bus from the North Exit of Tachikawa Station round to the Sunagawa entrance, or entering from Nishi-Tachikawa Station, is the realistic choice.

Besides the Forest of Mist, Showa Kinen Park has other summer water. But to see it, you need to get up a little earlier than the mist.