My Personalities Are Incredible Actors [Card Roleplay]

Modern supernatural horror, female-oriented fiction with a male protagonist and no romance, ensemble cast, secret identities, and rules-based infinite flow.

Ten years after supernatural horrors descended upon Earth, a young man raised by those horrors since childhood opens a weapons shop through his own hard work, hoping to settle into retirement.

Instead, a Secret Identity System unexpectedly binds itself to him. It wants him to gain renown by playing different personas and help this world's protagonist teams save the world.

As a seasoned psychiatric patient, he finds the Secret Identity System right up his alley.

Twins born together but destined to die apart, a young nobleman who lives for amusement, a writer who has lost his voice, a seemingly innocent but secretly sinister puppet master, the language of a rose blooming among thorns, a boy with both human and feline forms, a seer who sees through everything, an utterly rational prison warden...

Every persona has a madness of their own.

The protagonist teams: "...Where did all these lunatics come from?"

Later, they discover that behind all these personas stands a single mastermind. They call him Master and worship him as a "god."

Note: The personas are loyal only to the original self. The protagonist has no romantic pairing and mostly operates behind the scenes, with a slight everyone-loves-him element.