In the fabricated city of "Arcadia", humanity is not the sole master. In the shadowy places where they dwell, countless strange species coexist with humans. These bizarre, otherworldly beings are mostly found in the "Black Forest", on the outskirts of Arcadia.

Some pose a threat to humans, while others are completely harmless.

The "Limbo Project" and its eponymous facility were built precisely to imprison and study those otherworldly beings who have caused actual harm to humans. However, the Limbo Project's classification is top secret, so publicly, it is known as a maximum-security prison for heavy criminals serving special sentences.

Encountering the Extraordinary in the Ordinary

"I don't want to graduate and immediately be unemployed!"

With such a cry, the new graduate, Moqi Jie, luckily (or perhaps unluckily?) found an internship—working as an Ethics Supervisor in a mysterious prison located in her hometown.

The Warden and her adjutant are warm and approachable, and the compensation package is quite good. Moqi Jie is very satisfied with this job—that is, until she encounters a heavy prisoner in the prison who bears an uncanny resemblance to her missing younger sister.

No way! My sister isn't this terrifying! 

The Warden makes a special request of her: "Please teach that one. Make a beast into a human".

The heavy prisoner, who looks just like her sister, tearfully pleads with her: "Onee-chan, why did you only find me now?"

Her childhood friend demands she move in with him: "Jie, that person is absolutely not your sister".

Is this 'Limbo' even a legitimate prison? 

Limbo hides countless secrets. You must handle their forthright and passionate feelings with care.

After all, their fates rest in your hands.

The souls trapped in Limbo weep day and night. Will they ultimately ascend to heaven...?

Or will they fall into hell.

Sin and salvation—both depend on—your choice.