Bagi once ruled the ancient civilization of Old Mugen before its descent into the abyss. Consumed by resentment towards the new Mugen that rose afterward, she dedicated herself to its utter destruction and the resurrection of her sunken kingdom.

To achieve this, Bagi enacted a long-term scheme by corrupting Chocolat, the Spirit of the Cats. She exploited Chocolat's bitterness over disqualification from the Eto Ranger selection race – a disqualification Bagi engineered by fabricating a false vision of Princess Aura, tricking Chocolat into starting early. This manipulation twisted Chocolat into Nyanma, Queen of the Jyarei Monsters. Under Bagi's command, Nyanma unleashed Jyarei Monsters to corrupt the Novel Worlds, aiming to collapse the Novel Pole and drown the new Mugen beneath the sea.

Throughout the conflict, Bagi remained the hidden mastermind behind the Eto Rangers' struggles, directing Nyanma from the shadows. As the Jyarei God, she stood as the ultimate evil opposing Mugen's guardians. Her plans were consistently thwarted by the advancing Eto Rangers, leading her to abandon Nyanma when they breached her fortress.

In the final confrontation, Bagi possessed the corrupted mechanical pegasus Black Kirinda to battle the Rangers directly. She faced Bakumaru, the Eto Rangers' leader, during this clash. Ultimately, the combined efforts of the Eto Rangers and Nyanma – who turned against Bagi after realizing her manipulation – destroyed her. This union purified the corruption and ended Bagi's threat permanently.

Her character arc concluded with her final defeat, solidifying her role as the foundational antagonist whose actions catalyzed the series' central conflict.