In Legend of Heroes III: Song of the Ocean, players assume the role of a traveling musician named Forte. As in most RPG titles, gamers must guide Forte and his band of friends through a variety of environments as they search for a common goal. Forte is the owner of a mysterious map that shows the location of musically powered resonance stones. As Forte searches for the rock relics, he must defend his party against monsters roaming in the wild and complete a variety of side quests throughout the journey.
Gamers may attack monsters or avoid them, and during battle players can control up to four members of their group. Each character can be used to execute basic attack moves, cast spells, or take a defensive stance. During the game, players will notice a kind of pet traveling with their party. If the animal is treated well and fed it will become an ally during battle. For example, a well-fed rabbit has a habit of healing group members during combat. Players who have saved data from previous games in the series will find an extra mode where characters from former titles may be used during a fight.