This canonically unnamed woman appears in Final Fantasy Adventure and Adventures of Mana, but is only mentioned in Sword of Mana. In all three versions of the tale, she is both Fuji's mother and her predecessor as the spirit of the Mana Tree, and in Sword of Mana and Adventures of Mana she is also Bogard's lost love.
Final Fantasy Adventure / Adventures of Mana
Upon successfully delivering Fuji to Sir Cibba in Wendel, Sumo bears witness to a ritual involving Fuji's pendant, which summons the image of a motherly-looking woman, whom Cibba recognizes as a woman from the Vandole Empire who helped the Gemma Knights defeat Emperor Vandole many years prior, and whom Fuji herself recognizes as her own mother.
Later, she appears to Sumo as he enters the Mana Shrine from the Temple of Mana. She praises him as a true Gemma Knight and awakens Excalibur for him to use in his imminent battle with Julius.
After Julius is defeated and the Mana Tree is lost, Fuji's mother appears and reminds Fuji that, as maidens of the Mana Clan, the two are seeds from which a new Mana Tree can grow, should the existing one be lost, as this one was, as was the previous Mana Tree, which was replaced with Fuji's mother, who offers Fuji the choice of either becoming the new (and potentially last) Mana Tree, or returning to the world with Sumo to watch it all come to an end. Fuji decides to become the Mana Tree.
Similarly, her mother swears Sumo to service as the new Gemma Knight, defending Fuji from evil and ensuring she is never corrupted by evil, which he accepts. After which, she asks him to deliver a message to Bogard, who was in love with her, saying that she loved him too.
Sword of Mana
Sword of Mana expands the mother's role greatly, even giving her the name "Mana" to go with it, but reducing her presence to mere mentions by various characters who knew her.
Mana is Elena's birth mother, as she is raised by Elise after Mana vanished. Though she helped the Gemma Knights defeat Vandole and mothered Elena with Bogard, she knew her fate was to join with the Mana Tree and keep it alive so that Mana can persist and the world can survive, and refused to run away from it, not even when Bogard begged her to be with him.
- Fuji's Mother on Final Fantasy Wiki.