"Le Portrait de Petit Cossette" is a three-episode anime OVA that blends gothic romance, psychological horror, and supernatural mystery. The narrative centers on Eiri Kurahashi, a young art student working in his uncle’s antique shop. While examining a Venetian glass, he becomes entranced by the image of a girl named Cossette d’Auvergne, who appears to be trapped within the glass. Cossette reveals that she was the muse and lover of a 18th-century artist, Marcello Orlando, who murdered her in a fit of jealousy. Her soul has lingered within the glass for centuries, seeking someone to atone for Marcello’s sins.

Eiri becomes obsessed with Cossette, drawn into her tragic world and compelled to relive her memories of abuse and betrayal. As their connection deepens, Eiri learns that to free Cossette’s soul, he must endure the same suffering she experienced, taking on the burden of Marcello’s crimes. This leads to a series of surreal and harrowing experiences, where the boundaries between reality and illusion blur. Eiri’s sanity is tested as he confronts visions of violence, guilt, and despair, all while being pursued by Cossette’s vengeful spirit, which manifests in increasingly disturbing ways.

The story explores themes of love, sacrifice, and redemption, as Eiri grapples with the moral and emotional weight of his decision to save Cossette. Supporting characters, such as Eiri’s friend Shouko and his uncle, provide grounding in the real world, contrasting with the ethereal and nightmarish realm Cossette inhabits. The series culminates in a climactic confrontation where Eiri must fully embrace his role as Cossette’s savior, risking his life and sanity to break the curse and grant her peace. The resolution is ambiguous, leaving the nature of their bond and the ultimate fate of their souls open to interpretation.