Madama Styx, also known as Decider of Ends, is the name of the Infernal Demon who Jeanne has made a pact with in order to gain increased knowledge and power as an Umbra Witch. A supposed ruler of the river her namesake is derived from & a counterpart to Madama Butterfly, Madama Styx initially appears through the Wicked Weaves that Jeanne uses in her battles.Madama Styx eventually appears in her entirety when she's summoned during Umbran Climax and finishing summons in the second game. In the third installment, Styx acts as a Demon Masquerade form that Jeanne uses when fighting alongside Bayonetta, as well as an ally she can summon and control in battle using the technique known as Demon Slave.