Kajima Corporation is building “KAJIMA TREE” as one of the Village pavilions at GREEN×EXPO 2027. Its structure reuses timber from the Grand Ring at Expo 2025 Osaka, Kansai, and Kajima is one of the recipients of that timber. The building site is Kajima’s exhibit area inside the Expo grounds, in Yokohama’s Seya Ward.
KAJIMA TREE among the Village pavilions
The venue is run by the GREEN×EXPO Association (formally the 2027 Japan International Horticultural Expo Association). It describes the Village exhibits as a co-creation programme that combines displays with hands-on experiences. Companies and groups put up pavilions in five Villages on the grounds, each working toward the Expo’s theme, “Scenery of the Future for Happiness.” The Association’s page introduces 12 Village pavilions in all, and KAJIMA TREE is one of them.
The same page describes Tokyu Group’s “Tokyu Group Pavilion” as proposing a new lifestyle where nature and the city merge, and KT Group’s “KT GROUP Mobi+” as vehicles carrying energy to where it is needed. KAJIMA TREE’s building material, the Grand Ring’s timber, already existed.
A tower built from the Grand Ring’s timber
According to the Association’s page, KAJIMA TREE is a symbol of GREEN×EXPO that tells a story of tomorrow for nature and people. The page says it is built from timber used in Expo 2025’s Grand Ring, put to use again through advanced technology. It also notes that Kajima is a recipient of the Grand Ring’s timber.
Kajima’s dedicated site presents KAJIMA TREE in the same way. Kajima Corporation is a Village exhibit partner of GREEN×EXPO 2027, and the site calls the building a tower representing new scenery for future city-building.
Construction technique and scale
According to Kajima’s site, the structure of KAJIMA TREE reuses Grand Ring timber. The site says the building combines the beauty of traditional Japanese architecture with Kajima’s own advanced technology, and that its structure is built to flexibly absorb energy from wind and earthquakes.
On scale, the site gives a height of roughly 60 metres, comparable to a 20-storey apartment building, and calls it one of the largest reclaimed-timber buildings in Japan. It presents the project as part of a wider effort toward decarbonisation, resource circulation and nature-positive outcomes.
Before construction began, a 1:100 model of KAJIMA TREE was unveiled on 13 May 2026 at an event called the Non-Residential Wooden Construction Fair 2026.
Kajima Corporation set out how the timber is processed when it announced the start of main construction on 15 September 2026. Timber taken from the dismantled Grand Ring is cleaned, worked and polished at a processing plant, then fitted with seismic damper hardware before it becomes a structural column or beam. Units made of these worked columns and beams are assembled in advance, a method called jigumi.
The foundation concrete uses paving blocks made from CO2-absorbing concrete left over from Expo 2025 Osaka, Kansai, along with material from demolishing Kajima’s former Yokohama branch office.
The same announcement gave a completion target of the end of February 2027. What visitors will see or do inside, and when they will be able to go in (the Expo opens on 19 March 2027), had not been announced as of September 2026.
Timeline of announcements
| Date | Announcement |
|---|---|
| 13 May 2026 | A 1:100 model of KAJIMA TREE was unveiled at the Non-Residential Wooden Construction Fair 2026 (per Kajima’s site) |
| 1 June 2026 | Groundbreaking for KAJIMA TREE (announced by Kajima on 9 June) |
| 14 September 2026 | Main construction began and the site was opened to view; Kajima gave a completion target of end of February 2027 (announced 15 September) |
For the full pavilion lineup, see our feature page Pavilions.
Correction (19 September 2026): in “Timeline of announcements” we had said construction of KAJIMA TREE broke ground on 9 June 2026; in fact groundbreaking took place on 1 June, and 9 June was when Kajima Corporation announced it.