Tanaka Mamoru

Assistant lab director at Okoshi Pharmaceutical, working directly under Kenji Osawa. His faithful commitment to his work has managed to earn Osawa's trust, acting as his confidant during the kidnapping case and in regards to the blackmail e-mails. He shares an undisclosed relationship with Hitomi Osawa and acts as her primary relay contact during the case.

Spoiler

In truth, Tanaka is a traitor to Okoshi Pharmaceutical and works directly under Alphard to steal the Ua antiviral. The former lover of Osawa's current wife, Ai, he resents Osawa and has worked with Alphard to undermine him.