[You have defeated all appointed magicians on your own]
[You have passed the Sub Story.]
[As the main contributor, you have received 3000 coins as compensation.]
[You have received the qualifications to enter the secret room.]
Finally, I managed to take out all the girls that had been brainwashed. Naturally, I did not kill them and only knocked them out but it seems to be enough to pass the sub nightmare.
Fortunately, that guy was not specific enough and an <Error > was created as a result. Thus, I made use of that error to pass the trial. More importantly...
"I only received 3000 coins? Tck! I thought I would get around 10,000 coins at least."
[The constellations says you should not be too greedy.]
Perhaps I was being too greedy. In the first place, taking out these girls was just a sub Trial, not the main Nightmare. Expecting to get 10,000 coins in a sub nightmare was a sweet delusion.