This walkthrough will guide you through completing Sage's side story, which can be found on Kronos Island, Ares Island, Chaos Island and Ouranos Island.
Side Stories - Sonic Frontiers Guide - IGN
Sage Side Story - Sonic Frontiers Guide - IGN
Sonic Frontiers Guide - IGN
Amy Side Story - Sonic Frontiers Guide - IGN
Sonic Frontiers Review - IGN
Sonic Frontiers Story 1st Look + Sonic & Sage Character
Sonic Frontiers Guide - IGN
Sage Side Story - Sonic Frontiers Guide - IGN
Sonic Frontiers, Sonic Wiki Zone