1x3 - Who Killed Daigoro Tokuyama?

The body of their dead homeroom teacher, Daigoro Tokuyama, is gone! As the perplexed students (Keyakizaka 46) peer into the empty locker, they receive another message from Tokuyama. But Tokuyama is dead; who moved him? The next day, a mysterious woman appears. She seems like she is probing for something. Does she know about the corpse? But no, she's looking for something else...