Birdy the Mighty: Decode

A string of murders with dead female victims with short hair and glasses leads Birdy to investigate them with Tsutomu. The culprit is revealed to be a rogue combat marionette, which is killing the victims as it thinks of them as the mother, the main programmer when the marionette was placed under her care. Birdy attempts to retrieve it, but is attacked by supposedly a Federation-based person with a guardian robot that attacks her to keep her away from acquiring the disabled robot.