null² (; pronounced "Nurunuru") is one of the 8 "signature" pavilions at the Osaka-Kansai Expo 2025. It was produced and directed by media artist Yoichi Ochiai . 
The exterior sculptural design was created by Yoichi Ochiai and NOIZ architects. The theme of null² is "Forging Life", and it was designed to be an architectural embodiment of Ochiai's concept of "Digital Nature".
Name and concept.
The pavilion's name "null²" originates from the concept of "null" (undefined state) in computer science, combined with the philosophy of "form is emptiness, emptiness is form" () from the Heart Sutra in Buddhism. Yoichi Ochiai explains the meaning as "emptiness²" (emptiness (is form, form is) emptiness).
The pavilion is based on the concept of "two mirrors" – a "digital mirror" and a "physical mirror" working in combination.
Use of mirrors.
Ochiai, who became a producer in July 2020, stated that his motivation to create works with transforming mirrors as a motif stemmed from his creation of installation works featuring mirrors that float, rotate, and distort landscapes. Exterior view, Interior view. Produced by media artist Yoichi Ochiai, the pavilion features works expressing his concept of "Digital Nature", which follows and updates his previous works.The pavilion's theme is "Polishing Life," with production inspired by mirrors such as bronze mirrors that are polished before use. Yoichi Ochiai mentions that in contrast to Taro Okamoto's Jomon period symbolism presented through the "Tower of the Sun" at the 1970 Osaka Expo, he presents mirrors as a "Yayoi motif" for the 2025 Osaka-Kansai Expo.
Construction.
Yoichi Ochiai took the role of the chief architect during the construction, and the pavilion was designed by , , and the Arup Group. Fujita & Yamato Lease JV won the bid and constructed the pavilion. The pavilion was completed on 3 April 2025 along with the other seven signature pavilions.
Architecture.
The exterior of null² consists of a structure of various-sized cubes (voxels) covered with a special mirror membrane. This mirror membrane is a newly developed material that physically transforms through internal robotic arms and acoustic vibrations, creating a "moving architecture" that changes reflected landscapes.
There are two types of mirror membranes: flat ones and horn-shaped (concave) ones, each creating different reflection effects. When the mirror surface is stationary, it simply reflects the surrounding scenery, but when deformed by internal mechanisms, the reflected scenery ripples and fluctuates.
Exhibition.
null² aims to provide "unknown landscapes and experiences through interactive structures and digitalization of the body that humanity has never seen before". Inside, there is a theater space with walls covered in mirrors and ceilings and floors covered with LED panels, providing an experience where visitors' 3D scan data-based digital avatars interact with CG imagery. The pavilion also serves as a "sculptural monument," allowing for an experience even without entering the interior, just by viewing the exterior.