An elite high school had another face hidden in the dark side. In return for sending sex slaves to the colleges, they receive a lot of money as contributions. Those who trained sex slaves were disposable teachers (trainers) who could keep the secrets. They hired talented men as temporary teachers to train. If they found a promising person, they made him take a test. The test was to lecture those who were defined as problem students. However, lecture is merely nominal, and actually it was training for sex slaves. If he achieved a good result, he would get a qualification of teacher (trainer).