Midori Azuma is the wife of scientist Dr. Kotaro Azuma and mother to Tetsuya Azuma, the cyborg hero Casshan. Captured by the Android Army following the rebellion of BK-1 (Buraiking Boss), Midori's consciousness and biometric data are forcibly transferred into Swanee, a swan-shaped robot companion kept by Buraiking Boss, to ensure her compliance and survival.

Imprisoned within Swanee, Midori covertly observes Buraiking Boss. She communicates with Casshern through moonlight-activated holographic projections, delivering strategic guidance, warnings, and emotional support during his fight against the Android Army. Her presence within Swanee remains hidden from Buraiking Boss for most of the conflict.

In the 1973 series, her consciousness is restored to her original human body after the Android Army's defeat, allowing a reunion with Casshern, though her son remains a cyborg.

The 1993 OVA *Casshan: Robot Hunter* depicts her murdered by robots during an attack, an event haunting Casshan. Her ghost appears as a spiritual guide, significantly influencing his decision to stop the Black King's "Sigma Project" to replace humanity with androids.

The 2004 live-action film *Casshern* reimagines Midori as a blind woman afflicted by a degenerative illness. Dr. Azuma attempts to cure her using "Neo-Cells," but she dies off-screen after learning of Tetsuya's death in war. Her death intensifies Dr. Azuma's resolve to resurrect their son, indirectly triggering the film's central conflict.

Across all versions, Midori embodies maternal sacrifice and acts as a moral anchor for Casshan/Tetsuya, whether as a hologram, spiritual presence, or motivating memory. Her captivity or death consistently catalyzes crucial narrative developments tied to Casshan's identity and mission.