Ms. Toriumi is the home room teacher of Class 2-F in Persona 3. She is a language teacher for the junior class at Gekkoukan High School. Ms. Toriumi is an avid player of an old MMORPG known as Innocent Sin Online. The protagonist can form a Social Link with her after he receives a copy of the game from Junpei Iori. Toriumi, using the handle Maya (a reference to Maya Amano), convinces the protagonist to use the handle Tatsuya (A reference to Tatsuya Suou). "Maya" and "Tatsuya" talk through Toriumi's grievances at work, and she eventually develops a crush on the protagonist. When Innocent Sin Online administration announces that the servers will all be shut down, she plans on sending her and the protagonist's chat logs to them in order to prevent them shutting down the game.

Ms. Toriumi is a laid-back teacher who is often at odds with Mr. Ekoda. She is extremely fond of cake and she at one point tells a student that they need to bake her a cake to turn in with one of their assignments. Other teachers at Gekkoukan have mentioned they would bring her cake whenever they needed to talk with her so she'd be in a good mood. Although she loves nearly all cakes, she doesn't like Mont Blanc.

Ms. Toriumi and Mrs. Terauchi occasionally play Mahjong together after work. Terauchi is only a novice at the game and Toriumi is teaching her Mahjong terminology, something which Terauchi is very excited about. However, from her descriptions of the games, it seems Toriumi is taking advantage of her inexperience and cheating to win. Supposedly, Toriumi has never lost a match.

At the epilogue of the Social Link, the Protagonist can go into the Facility Office to find Ms. Toriumi. The Protagonist would drop his cell phone, which now has the background of Maya's message in the sand to Tatsuya. Ms. Toriumi picks it up, and sees the picture, pretty much shocked. However, even through her age, Ms. Toriumi finds it within herself to accept the Main Character as the person she loves, and tries to ask him for a dinner. However, she still storms out of the office, angry.

Her arcana is the Hermit.