The female protagonist of Persona 3 Portable, canonically known as Kotone Shiomi is a transfer student enrolling in Gekkoukan High School on Tatsumi Port Island. She is an orphan whose parents died on the Moonlight Bridge in their car during a fatal incident a decade prior to the game.

She is very bubbly, funny, upbeat and cheerful. Her dialogue choices exhibit a broad spectrum of emotions, ranging from sarcasm, joking tones, utter seriousness and otherwise depending on the player's choice. She is outspoken, blunt and literal when responding and getting her points across. She is a sharp contrast to the male protagonist who is very reserved and concise where she, on the other hand, is not afraid to interject into conversations where her male counterpart would remain silent. In addition, she is more likely to resort to violence when provoked, especially in defense of her friends, as seen in her Hermit Social Link. She is often described by the S.E.E.S members as a very tomboyish leader who takes risks to save her friends.