Koju Koju no Mi

The Koju Koju no Mi ( 我々 我々) is a Paramecia type Devil Fruit, in which the user can have full control of their thyroid gland. Koju for “Thyroid”, in both Viz Manga, and the FUNimation dub, it is called the '''Thy-Thy Fruit. '''

Strength and Weakness
The user gains a full control over their thyroid gland, in which the user can basically manipulate their own body. At first when this fruit was introduced, the user could only make their muscles expand and grow. Basic things, however over the years of training the user could manipulate the thyroid to do almost anything to the body. The user will suffer the standard weakness of the devil fruits.