Miharidai

 is a sword that was crafted long ago on the island of Wano. The blade was used in many wars and eventually became a symbol of good fortune. It was held atop a tower that gazed over the land, people believed that if it watched from above they would be safe. Eventually that belief proved false as Kaido took over Wano. During his reign the sword was found and used as a test subject in weapon experimentation and Miharidai was given the Puri Puri no Mi, Model: Sourei. With sentience gained, the Miharidai briefly served with a subordinate of Kaido's. Though the blade wished not to bring ruin to the land so it killed him and set off to protect Wano in its own way. Many years later after Kaido fell Miharidai left Wano, feeling its job completed. It began to roam and truly explore what sentience was like.

Devil Fruit
Miharidai possesses the Puri Puri no Mi, Model: Sourei, giving it the powers of poltergeist. Unlike most zoan, Miharidai does not transform its own body into a poltergeist. It instead creates a spirit beside it that takes whatever human form it wishes. This spirit acts as the full or half zoan form of the blade. The spirit can interact with physical objects and speak in whatever voice Miharidai wishes, often taking forms of people or spirits it encounters. Most never assume that Miharidai is actually sentient as the spirit can is indistinguishable from a human unless it is using its powers. Of course at that point most assume the human is just a devil fruit user, not the sword.