Google translation from Amazon.co.jp description:
Seventeen years ago, seven subjects of the Japanese government's Siegfried project went missing, calling themselves phantoms and hitting the government with a challenge. The murderer, Mami Kurusu, gets into Kuzu High School, which seems to be phantom-related! ??
The Doujinshi & Manga Lexicon
[Vol. 1](https://www.doujinshi.org/book/293410/)
[Vol. 2](https://www.doujinshi.org/book/293420/)
Vol. 3
