Nightmare×BlackCat ～追忆的彼岸～（Nightmare×BlackCat ～追憶のビヨンド～）

Gen'yousai was an ancient calamity that was responsible for the death of Amou Hibiki's parents. Learning this, Hibiki was determined to chase Gen'yousai down.

In order to face Gen'yousai's great power, Hibiki set out to find the sacred artifact "Magatama of Prosperity." She sought help from Mizuki Minako, who was knowledgable about sacred artifacts. Minako was a former exorcist and an acquaintance of Hibiki, famous for her extraordinary knowledge. She had retired a while ago, but was said to be studying sacred artifacts recently.

However, when visiting Minako's house, Hibiki learned that she had passed away. Minako had been a mentor figure for local children, and even now her house was a gathering place for the children. At the recommendation of the current caretaker of Minako's house, Hibiki decided to stay at the house for a while to look for clues about the magatama.

On one such day, Hibiki met a strange girl. The girl had soft, golden eyes, and she introduced herself as Mikazuki Megu, offering to to assist Hibiki in her search. Megu turned out to be a nekomata who owed a debt of gratitude to Minako and was protecting her house even now.

Hibiki, who Megu had unexpectedly taken attachment to, decided to search for information about the magatama together.

Things should've gone calmly and smoothly from there, but for an unknown reason, Hibiki and Megu were assaulted by a local gang who seemed to know about Hibiki and Megu's "power." The two were unable to use their power normally, and ended up being taken captive...

[Translated from the official website]