Mistress

A mysterious woman with a bewitching atmosphere.

She claims to be the one who abducted the protagonist, Miyu, and the others to the basement, and calls herself "Mistress".
Her manner and tone of voice are polite and gentle, but she will not tolerate refusal of instructions or disobedience to orders.
If you disobey her, she will punish you severely and without mercy.
She puts the hero and heroines through unreasonable "ordeals," and seems to enjoy watching them on her monitor.
Why does she do it and why were the hero and heroines brought to the basement? The purpose is unknown.