null⁴ (TetraNull)

“null⁴ (TetraNull),” produced by media artist Yoichi Ochiai, is a “landscape-transforming sculpture” that will appear in the SATOYAMA Village at GREEN×EXPO 2027. It carries on the experience and philosophy of null², the signature pavilion Ochiai created for Expo 2025 Osaka, Kansai, and the Expo Association calls it a new “life sculpture pavilion.” Its theme translates as “What we inherit is not form, but karma.”

Highlights and exhibits

The Expo Association describes null⁴ as mirrored life sculptures that rotate while reflecting flowers, sky and visitors, creating an ever-changing landscape — a “computing garden” where nature, people and digital technology mix. A July 14, 2026 announcement explained that four mirrored bodies will rotate while reflecting their surroundings, showing different faces by day and night and through the seasons. The work does not alter the landscape itself; instead, reflection updates how the world is seen. The artwork’s website (null4.art) shows the sculpture lifting the colors of flowers by day, reflecting the sky at dusk and becoming a sculpture of light at night. Each of the four bodies turns with a slightly different logic, and visitor instructions are “still in development and will be announced soon” (checked October 4, 2026).

In a September 14 note post, Ochiai summarized the current plan he presented to sponsors (all subject to change):

• Four structures, each about 6 to 9 m tall; three of them rotate, with the architecture sitting on a rotating base
• Nearly cornerless forms made with membrane structures, metal frames and deforming membranes
• GPU servers in each structure running local AI that learns from its surroundings, with power generated from solar and other natural energy
• The garden is the main attraction, and the moving sculpture is best viewed from around it

null⁴ is also linked to null²ⁿ (Null Null Nexus), a permanent theater in Yokohama. Experiences and data from null²ⁿ will carry over to null⁴, with joint plans to be announced. Visitors who download the Mirrored Body® app in advance, used by 170,000 people at Expo 2025, will see their digital avatars sync with the spaces at both sites.

Building and design

• Form: a landscape-transforming sculpture of four movable mirrored bodies using a stretchable mirror membrane with 98% reflectivity (artwork website).
• null⁴ is described as neither a relocation nor a copy of null², but a new living sculpture that inherits the ideas of mirrors, rotation and emptiness.
• In July 2026 the Expo Association began seeking sponsors for building the work (structures and moving mechanisms, video and sound equipment, planting, interior work) and for operations (security, cleaning, visitor guidance).

About the exhibitor

The work is planned by Digital Nature and Arts, a general incorporated association founded around Ochiai after the creation of null² to produce, record and pass on works based on the idea of “Digital Nature.” The Expo Association says it is developing null⁴ together with Ochiai’s team. Ochiai is a professor at the University of Tsukuba and served as a theme project producer for Expo 2025 Osaka.

Announcements so far

• Mar 19, 2026: The name “null⁴ (TetraNull)” was made public, one year before the opening (Ochiai’s note).
• Apr 7, 2026: null⁴ and null²ⁿ were announced, and the null⁴ website opened with calls for donations and sponsors.
• July 1, 2026: The Expo Association began seeking sponsors for the null⁴ project.
• July 14, 2026: A joint announcement detailed the four mirrored bodies, the theme, and null²ⁿ’s October 14 opening.
• Sept 14, 2026: Ochiai described the current plan, including the height and rotation, in a note post.
• Sept 15, 2026: A null⁴ page was added to the Expo Association’s official website (announced by the null⁴ X account).
• Oct 14, 2026: null²ⁿ opens on the 5th floor of Yokohama Landmark Plaza.

On social media

The official null⁴ account on X (@expo2025_null2, carried over from the null² era) shares updates such as the new official page and null²ⁿ news. On X (formerly Twitter), many people who experienced null² in Osaka say they are looking forward to null⁴, and posts often mention it together with null²ⁿ’s October opening (as of October 2026).

Before you go

• Location: SATOYAMA Village. On the venue map on the Expo Association’s UR page, null⁴ is shown near the UR area at the southeastern edge of the venue.
• Reservations: Which exhibits will use same-day “viewing reservations” has not been announced (as of October 2026).
• Related facility: null²ⁿ (5F Yokohama Landmark Plaza) is separate from the expo, with its own date-and-time tickets; a visit takes about 60 minutes. Tickets: adults (13+) ¥3,900 weekdays / ¥4,500 weekends and holidays; children (4–12) ¥3,000 / ¥4,000; ages 3 and under free (one per adult). Children under 12 must be accompanied by an adult (18+, up to 3 children per adult). Open 9:30–21:00.
• Support: Donations (from 10,000 yen per unit, until September 26, 2027) and sponsorships are accepted on the official website.

Sources:

• Expo Association: null⁴ (TetraNull) project page (Japanese) and UR page with venue map (Japanese) (checked 2026-10-04)
• null⁴ official website (English) and Japanese site (checked 2026-10-04)
• null⁴ artwork website, null4.art (checked 2026-10-04)
• Expo Association press release, July 1, 2026 (PDF, Japanese) (checked 2026-10-04)
• Joint press release on null²ⁿ and null⁴, July 14, 2026 (PDF, Japanese) (checked 2026-10-04)
• Yoichi Ochiai’s note posts: Mar 19, 2026, Apr 7, 2026, Sept 14, 2026 (Japanese, checked 2026-10-04)
• null⁴ official X post, Sept 15, 2026 (checked 2026-10-04)
• null²ⁿ official website (checked 2026-10-14)

Note: exhibits and highlights will be updated as official announcements are made.