Rainbow-Colored Past - S1.E4

The helicopter's radio has been smashed, apparently before Shindō could use it. Computer records show that no one accessed the roof between the time when Shindō and Miki arrived and when Shindō was found dead. Saikawa, Nishinosono, Yamane, and the lab security guards enter Magata's suite and discover a small robot in the bedroom. The robot's only physical capability, other than basic mobility, is to lock and to unlock the bedroom door. The robot's name is Michiru, the same as Magata's favorite doll.