"Galaxy Express 999: Glass no Clair" is a two-episode OVA that serves as a sequel to the original "Galaxy Express 999" series. The story is set in a distant future where humanity has achieved immortality through mechanical bodies, and the titular Galaxy Express 999 is a space train that travels across the galaxy, offering passengers the chance to obtain these mechanical bodies on the planet Prometheum. The narrative centers on Tetsuro Hoshino, a young boy who embarks on a journey aboard the 999 to avenge his mother's death at the hands of Count Mecha, a ruthless aristocrat who hunts humans for sport.

In "Glass no Clair," Tetsuro and his enigmatic companion, Maetel, encounter a mysterious girl named Claire, who possesses a fragile glass body. Claire is pursued by a group of mechanical beings known as the Black Knight Corps, who seek to capture her for reasons tied to her unique existence. As Tetsuro and Maetel protect Claire, they uncover her tragic backstory: she was created as an experiment by a scientist who sought to merge human emotions with mechanical perfection. Claire’s glass body symbolizes her fragility and humanity, contrasting with the cold, unfeeling nature of the mechanical world.

The plot delves into themes of identity, humanity, and the consequences of immortality. Tetsuro’s journey is not only physical but also philosophical, as he grapples with the moral implications of mechanical bodies and the loss of human warmth. Claire’s plight highlights the tension between the desire for eternal life and the preservation of human essence. The Black Knight Corps serves as a formidable antagonist, embodying the oppressive forces of a mechanized society that values efficiency over emotion.

The OVA retains the melancholic and introspective tone of the original series, with Tetsuro’s growth as a character taking center stage. Maetel remains a mysterious and guiding presence, her motivations and past shrouded in ambiguity. Claire’s character adds a layer of poignancy to the narrative, as her struggle to retain her humanity in a mechanical world resonates with the broader themes of the series. The story concludes with a bittersweet resolution, leaving viewers to reflect on the cost of immortality and the enduring value of human connection.