Waveblade
Waveblade is found in a dojo in a tree south of the Temple of Droplets and west of the Major's Cabin in The Legend of Zelda: The Minish Cap. It is here that Waveblade teaches the Peril Beam technique to Link, and he can also upgrade the Great Spin by fusing Kinstones. In order to access this, Link must have the Flippers. Waveblade will not train Link unless he has ten hearts or more.