Sayaka Nakasugi invites her classmates to her mansion for her welcome back party. Birdy investigates the site where she had killed Tsutomu in order to locate a marionette of non-Earth origin. Sayaka's maid Yoshio finds strange things have happened to her, which started to worry Sayaka's grandfather, Katsutoshi. Meanwhile, Nakasugi disappears from the Nakasugi Mansion after encountering a parrot, which was an alien being in disguise.

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.

Nakasugi invites her friends including Tsutomu to her family village in the Sawajiri Village in Nagano. But on one evening, Nakasugi succumbs to the Riunka implanted on her by an unknown force who returned the renegade marionette back to her owners. A small number of Riunka explosions rattled the village, forcing local police and the JGSDF to mobilize.

An investigation team under Shyamalan's orders investigates the ruins of Sawajiri Village, even killing a policeman when Murota and Hayamiya decide to investigate. Birdy saves them from some of the armed men and fights the reconstructed marionette before she gets injured during an encounter with Gomez after defeating the marionette again.

Tsutomu and Nakasugi go on a date with Tsutomu received a kiss from Nakasugi herself. Meanwhile, Shyamalan meets with Sayaka's grandfather and kills him during the meeting. When Yoshie discovers his body, she thinks that Sayaka killed him, which activates the Ryunka in her body and evaporated her.

It has been confirmed: Nakasugi is the host for Ryunka. But Tsutomu wants to protect her, no matter what and so he takes control of Birdy's body when she tried to get close to Ryunka. Nejula knocks them out before their minds fuse completely. When they wake up again, Tsutomu has his own body back and needs glasses again. From now on, Birdy and Tsutomu go separate ways. When Birdy and Nejula arrive at Nakasugi's villa, she is already gone because she went to Tsutomo's place. To protect her from being pursued by her greedy relatives, Tsutomu leaves her in Shymalan's care. After that he discovers Shymalan's true intentions when Nejula confronts him...