Alicia appears as a young girl with long pink hair in twin ponytails and gray eyes, dressed in a blue outfit reminiscent of Lewis Carroll's Alice. Kimihiko Kimizuka discovers her sealed inside a container during a routine walk. Suffering identity amnesia, she claims to be 17 despite her childlike appearance and recalls nothing of her past. She displays a genki personality, energetic and excitable, often appearing or vanishing suddenly without explanation, a trait partially attributed to Kimihiko's temporarily impaired vision but extending beyond it due to her stealth capabilities.

Her story intersects with Siesta and Kimihiko when she unexpectedly joins them for a meal, struggling to chew hard carrots in Kimihiko's curry. During this encounter, she playfully requests Kimihiko place a ring on her finger in a mock marriage proposal, an act witnessed by a subtly jealous Siesta. Alicia also expresses enthusiasm about making Kimihiko her assistant, directly challenging Siesta's established partnership with him.

A critical revelation uncovers Alicia's true nature as an alternate personality of Hel, the primary antagonist leading SPES. This identity emerged after a head injury caused Hel amnesia and a physical transformation into a younger form. As Alicia, she remains unaware she is Hel, known for harvesting human hearts. One specific harvested heart, later transplanted into Nagisa Natsunagi, creates a subconscious connection and drives Nagisa's desire to locate Kimihiko. Alicia represents an unwitting manifestation of Hel, potentially a temporary state of innocence or redemption stemming from the amnesia.

The narrative confirms Hel reasserts control over their shared body, concluding Alicia's independent existence. However, the transplanted heart from one of Hel's victims persists within Nagisa, serving as a lingering influence connecting both characters.