This game is called Murder Mystery. The player becomes one of the characters in the story and searches for the culprit of the incident that occurs in the story. Since the criminal is also one of the players, the purpose is that the player who became the criminal does not know that he is the criminal.
Each player has his or her own purpose other than searching for the criminal or not knowing it, and each player aims to achieve multiple goals and win the points obtained by achieving them.
"Zero Ni Makoto" is a fictional story about the Edo period in Japan. Do you know the "Shinsengumi" who played an active part as a police in the Edo period? The Shinsengumi had units from No.1 to No.10, and systematically guarded the town of Kyoto. However, there was a "No. 0" that did not remain in history in the Shinsengumi.
"Zero Ni Makoto" is a story of the success and tragedy of Shinsengumi No. 0.
—description from the designer