Tenkuu Tenkuu no Mi

The Sei Sei no Mi (精精の実, "Aether Aether Fruit") is a Logia-type Devil Fruit that was consumed by Gai Nagareboshi. It allows the user to create, control, and become aether, which is also spelled æther or ether, the material that fills the region of the universe above the terrestrial sphere. Aether is the fifth classical element after earth, fire, water, and air.

Strengths and Weaknesses
The Sei Sei no Mi is known as the "Devil Fruit by which aether, the fifth essence of the universe, flows," in reference to how aether's natural form is a divider between spaces of the universe. By using this ability, Gai can emit aether in its most natural form causing air space or matter to split and eliminate natural forces. Gai can also focus aether in a way that it takes a physical essence, appearing like pure energy. From there, the energy can take on a variety of functions.