It Is Not a Relocation of null²: Yoichi Ochiai Explains the True Meaning of null⁴ and GREEN×EXPO 2027
©Yoichi Ochiai
I encountered null² (Null-Null) at Expo 2025 Osaka, Kansai, Japan.
When I stood inside that space,
I remember feeling less as though I were seeing “the future” and more as though every boundary were dissolving.
When I heard that null² would reappear as “null⁴ (Tetra-Null)” at the International Horticultural Expo 2027, Yokohama, Japan (GREEN×EXPO 2027),
I knew I wanted to hear the details directly from Yoichi Ochiai.
Why Does “null⁴ (Tetra-Null)” Have Four Pavilions?
©Yoichi Ochiai
I asked Ochiai the following question:
“I understand that null⁴ will consist of four pavilions,
and the number four also seems to echo the four seasons.
What idea led to this evolution from null² (Null-Null) to null⁴ (Tetra-Null)?”
Ochiai replied,
“Because it comes after null², we decided to go with null² squared—two to the second power. Four is a useful number for building many kinds of logic, and it also connects with Japan’s four distinct seasons.”
null² was Osaka’s presentation of “Digital Nature.”
In Yokohama, however, the idea is not simply to move it, but to let it be “reborn.”
To give the concept a breadth that null² could not fully express,
the result was a structure made up of four pavilions.
The term null⁴ did not come first.
It was the form that emerged as the underlying philosophy expanded.
When I heard that,
I thought, “So this is what an expo legacy can look like.”
null² Is Not Over
©Yoichi Ochiai
The signature pavilion null² at Expo 2025 Osaka, Kansai, Japan
was a space that dissolved the boundaries between digital technology and nature, AI and humanity, and the physical and informational worlds.
At SATOYAMA Village in Yokohama,
it will be “reconstructed within nature.”
As enormous objects rotate, they take in the landscape, light, and traces of human presence.
Rather than architecture, it is “a living sculpture that generates landscapes.”
That is why one building was not enough.
The four-pavilion composition feels like proof that the philosophy itself has expanded.
“Digital Nature” Expands at GREEN×EXPO 2027
©Yoichi Ochiai
GREEN×EXPO 2027
is centered on the theme of “coexisting with nature.”
Within the expo, null⁴
will be presented as a space that reconfigures the relationships among nature, human-made objects, computation, and people.
The null² born in Osaka will encounter a “forest” in Yokohama.
As an expo fan, this progression is genuinely thrilling.
An expo does not end when its scheduled run is over.
Ideas evolve as they move to new places.
We may get to witness that happen right before our eyes.
Mirrored Body and “Another Me”
The Mirrored Body app, experienced by 170,000 people in Osaka,
is also expected to play an important role again in Yokohama.
By downloading it in advance,
your digital double can connect with the space.
null² was never an exhibit you simply looked at.
null⁴ will surely become a “landscape you participate in” as well.
The ideas born at Expo 2025 Osaka, Kansai, Japan
will take the form of what kind of forest at GREEN×EXPO 2027?
As an expo fan, I hope to be there for that moment once again.
And “null²ⁿ (Null-Null Nexus)” Is Coming to Yokohama
Another keyword from the interview made my heart race: “null²ⁿ (Null-Null Nexus).”
Many people wanted to experience null² at Expo 2025 Osaka, Kansai, Japan but were unable to do so.
©Sustainable Pavilion
This permanent theater is being upgraded and installed so that both those visitors and people who loved the world of null² can enjoy it.
null²ⁿ will be approximately five times the scale of null².
Its program will include both content carried over from null² and newly created material.
A major upgrade is expected.
©Sustainable Pavilion
If null⁴ is a space that can be experienced during the special, limited period of an expo, null²ⁿ is the presence that connects its philosophy to everyday life.
It is being envisioned in Yokohama as a hub where people, nature, the city, and the digital world continue to intersect.
An experience born at an expo will keep evolving within society even after the event ends.
That is exactly the ideal form of the “legacy” an expo aims to create.
The excitement that first sprouted with null² in Osaka will bloom with null⁴ in Yokohama and take root in daily life through null²ⁿ.
As an expo fan, I cannot help but feel thrilled by this sweeping story.
Event Details
null²ⁿ (Null-Null Nexus)
Dates: Opening in 2026; planned as a permanent venue
Venue: Yokohama Landmark Tower
©Sustainable Pavilion
Registration is currently open for the advance-booking waitlist.
Priority booking is planned before general reservations begin.
Signing up is simple and requires only an email address.
null⁴ (Tetra-Null)
Dates: March 19–September 26, 2027
Venue: SATOYAMA Village at the GREEN×EXPO 2027 site
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