Zen'aku / 善悪

The protagonist has captured 4 women and confines them to an abandoned hostipal in order to expose and condemn the crimes that they commite.

These women are deeply involved in the deaths of his beloved younger brother and sister. However, they won't break so easily.

If they don't want to be upfront, then he will get the information out of them. Interrogation, torture... using any means possible to punish them thoroughly.