David Yost was part of the original cast of the first four seasons of Power Rangers. Since he left during Season 4, the series has undergone many, many changes, but now, in Season 30, Yost returns as a mentor for the Dino Fury Rangers.
Source：https://www.cbr.com/original-blue-power-ranger-david-yost-returns-to-the-franchise-for-cosmic-fury/
