Kamen no Otoko

Alongside Naenia and the Plague Doctor, Monsieur Spider infiltrated Marquis Machina's bal masqué in an attempt to assassinate Luca as Grand Duke Oriflamme while the guests were distracted with the four Curse-Bearers Naenia had afflicted with the Malnomen Dissonance. Monsieur Spider, alongside the rest of Charlatan, is known to be in association with Moreau, who has been kidnapping Curse-Bearers in pursuit of a means of transforming himself into a Vampire. Upon the discovery of Moreau's lab, Monsieur Spider saved Moreau from the likes of Vanitas, Noé Archiviste and the Chasseurs, intent on leaving the lab to be destroyed alongside the unwelcomed intruders.

(Source: Mochijun Wiki)