Trinity Glassfille, also known as Platinum the Trinity, was a member of the Six Heroes, who had her soul sealed within the Arch-Enemy Event Weapon, Thundering Roar: Muchōrin. Trinity is a prodigy in sensing and analyzing magic information and is able to project gathered information in the form of images floating above a magic circle. As one of the Six Heroes, Trinity possesses a great deal of knowledge of magic and alchemy as well as how to use them properly, earning her the title Platinum the Trinity.

During the Great Dark War, Trinity was known as Platinum the Trinity, and was part of the Six Heroes. She studied at the Magic Association alongside Celica Ayatsuki Mercury and Konoe Ayatsuki Mercury. Trinity was a key reoccuring character in the BlazBlue storyline, appearing in arcade and story modes over the years. Trinity was unveiled as a playable character of the game in 2026, nine years after the game's release in 2017.

She accompanied Nine in her search for the missing Celica. They were able to find her but Nine immediately attacked Celica’s companion, Bloodedge. Before things could escalate any further, Trinity was able to calm Nine down. She accompanied the group to First Area and encountered Hakumen, who recognized them as future allies before leaving. They later find Shūichirō Ayatsuki's lab and stumble upon many of his works, including Kushinada's Lynchpin. While the others searched for clues, Trinity took control of the security systems. When the Black Beast arrived at their location due to a nearby Kiln, Trinity and Nine offered to help Bloodedge combat the Beast, noting that fighting it alone is impossible. Bloodedge declined and had Nine teleport Celica, Trinity, and herself away while he and Mitsuyoshi took on the monster. The three girls waited at the Alucard castle for their comrades to return, though only Mitsuyoshi was able to come back from the encounter.

In BlazBlue: Centralfiction, Trinity separated her soul from Muchōrin and transferred it into Ice Sword: Yukianesa. She healed the wounds that Jin Kisaragi received when he fought the Black Beast Ragna, and he used his Power of Order to acknowledge Platinum the Trinity and prevent Luna and Sena from disappearing. Near the end of the game, she enabled Jin to use the Susanoo Unit by using her magic. After Ragna defeated Yuki Terumi, she used her magic to give Noel Vermillion some clothes since she was nude. Trinity also removed Jin from the Unit using her magic per Ragna's order as part of his deal. After Ragna consumes Jin and Noel's dreams as part of his plan to use the power of the True Blue in order to realize their dream, he asks Trinity to bring them back to their world. Trinity reveals that even if Ragna attempts to consume her "dream", it was already realized. She then takes the Susanoo Unit, mentioning that the discovery of this unit was the first "sin" made by humanity, which was beyond what human hands could handle. Conversing with Hakumen due to part of his soul remaining within the unit as a farewell, Trinity threw the Unit to the deepest part of the Boundary.