Chikara Chikara no Mi

The  Chikara Chikara no Mi  is a Logia class Devil Fruit that grants the user the ability to manipulate and emit Gravitons. It was eaten by "Fleet Admiral Graviton" aka Blair D. Danvers. Chikara means Force in Japanese.

User
Blair D. Danvers is the Fleet Admiral for the Marines and often is seen as a unbeatable force. During her time as Fleet Admiral she signed a agreement to form a group called "the Royal Seven Warlords" who consist of seven pirate captains who work for the world government. Blair is more commonly known as "Fleet Admiral Graviton" or "Lady Graviton" and is often feared for her powerful methods.

Strengths
This Devil Fruit can potenially be used to achieve anything and is only limited by how much the user can imagine to do with it.

Weaknesses
Unlike other Devil Fruit users Blair has no weakness making Blair literally Invincible. The user of the Jisha Jisha no Mi is able to counter some of Blairs ability, but not enough to completely stop her.

Usage
Blair despite being the most powerful of all Devil Fruit users hasn't been seen using her devil fruit due to her extreme measures used to capture pirates.