Chelsea Arcot is a Holy Knight of the Knights Templar. She becomes a member of Clan Oasis alongside Leicester Maycraft, engaging in their adventures throughout Ert'Aria. Professionally skilled in combat, she wields the large sword Celestine during crucial missions. Despite her knightly prowess, Chelsea struggles profoundly with navigation, frequently becoming lost even with destinations in plain sight. This directional impairment is a recurring trait, sometimes leading her onto entirely different continents despite intending only short journeys. Her navigational difficulties create an ineffective partnership with Garnet, a dragon avatar sharing similar challenges; their combined efforts often result in extended disappearances lasting until nightfall.

Chelsea maintains a friendship with Shelley Maycraft, Leicester's mother. Within Clan Oasis, she gradually develops romantic feelings for Leicester, revealed through their shared experiences. Early interactions display jealousy-fueled reactions when Leicester engages with other women like Carina Verritti or Minette, including incidents of fainting after he holds her hand and visible frustration when seeing him carry others. In moments of distress, she finds comfort with a golem created by Salsa Tortilla, its behavior modeled after Leicester.

Her combat ability surfaces during crises, such as improvising a candelabra as a weapon against crystalline threats when deprived of Celestine. For public festivals, she joins the Tortilla sisters in operating a maid café as part of Clan Oasis's community activities. Visually, she possesses distinctive long hair and appears in varied attire, including evening dresses for formal occasions.

An original video animation release, unrelated to the main series' storyline, features fanservice-oriented content involving Chelsea. No further narrative development or background details are documented across additional media adaptations.