There are three playable characters in Secret of Mana as well as a whole supporting cast of non-player characters;
Randi (a.k.a The Boy, The Hero or Randy) is the silent protagonist of the game, adopted by the Elder of Potos after being abandoned by his mother in the village. After pulling free the Sword of Mana, and releasing monsters across the world, he is banished in an attempt to protect the village. Seeking to restore the sword it's power, after being directed by a knight by name of Jema, Randi embarks on a quest to restore the blade to it's former glory.
Purim (a.k.a The Girl) is the spoiled daughter of an aristocrat of a kingdom who sends it's knights to defeat the dark witch, Elinee. She first meets Randi when he is ambushed by Goblins. Aiding his escape, she later runs in to him again outside Elinee's Castle. She is in love with a knight, Dyluck, who has been sent to destroy the witch on a suicide mission. Angry with the King, and also her father who has established an arranged marriage for her (not with Dyluck), she rebels and joins Randi in hopes that she will be able to find and rescue Dyluck. She aids Randi with defensive and support magic gifted her by the Elementals.
Popoie (a.k.a The Sprite) is a woodland sprite who was caught in a flood that took him to Gaia's Navel where the Dwarves live. He makes a living scamming visitors at the freak show. Inflicted with amnesia as a result of being caught in the flood, he joins the party in an attempt to find out who he really is. As an orphan as well, he empathises with Randi and understands most of the reasons for his actions. Popoie's gender has never officially been stated, however in the Japanese script he's referred to as "oira" which is mostly used when referring to a male speaker. He supports the team with a repetoire of offensive magic gifted him by the Elementals.