Why.. Not shinoda and tsutsui just leave from the hotel room? They dont have to act hero f...

yes and no to the blackmail. Tamura picked his victims wisely and they both were men with bleeding hearts and a slight hero complex (wanting to protect the other victim from the lying snake that is Tamura). So when they were fed the story that his past lover committed suicide in front of him and they both resembled the dead lover that was kind of blackmail to their personalities. As you're either gonna be an asshole leaving a man who has that kind of trauma and labeling him as evil or just roll over and show some compassion.

..... Also feel like that's why Tamura still has a job there, cause of multiple sob stories or Shinoda wants to keep him there to watch him so he can watch his next moves. Instead of being jumped in an alleyway and kidnapped cause Tamura seems very capable of doing that.

..... damn that was long