Lia Lagoon is a supporting character in the anime My Status as an Assassin Obviously Exceeds the Hero's. She is the former princess of the great nation of Peridot, a member of the Beastfolk, and is known for her distinctive husky-like ears and tail as well as her brilliant cobalt-blue eyes and short blue hair. She is of average height and bust and typically wears a red outfit resembling a mage's robes.

Lia Lagoon is a mysterious young woman who possesses knowledge about the hidden truth behind the hero summoning ritual and the circumstances that led the protagonist, Akira Oda, and his classmates to be summoned to another world. She holds the Guardian class and seeks out Akira specifically to deliver an important message to Amelia Rosequartz, thereby becoming a key conduit of crucial information early in the story. Her role in the narrative is that of a guide and information broker, helping to uncover secrets that drive the plot forward.

Her personality is described as warm and socially attuned, with a natural inclination to care for others. However, she is also marked by an air of mystery, as she initially keeps her full knowledge and intentions concealed. Her motivations stem from her royal background and the fall of her nation, though the exact details of her past and the events leading to her status as a former princess are not fully elaborated. Over the course of the story, she develops from a harbinger of secrets into a more direct ally to Akira and his group, using her intelligence and connections to assist in their mission.

Lia Lagoon's notable abilities are tied to her Guardian class, which suggests a capacity for protection and combat. Beyond this, her primary asset is her knowledge of the summoning ritual and the political dynamics of the world. Her Beastfolk traits, including enhanced senses, may also factor into her capabilities, but specific powers are not emphasized in the available information.