Correct Cardo

Shindou Yukiro is a capable negotiator working for the Ministry of Foreign Affairs. At Haneda Airport, as Shindou's passenger plane was preparing to take off, a mysterious huge cube appeared in the sky. "That thing" rapidly grew in size and swallowed the passenger plane carrying 252 people. The name of the giant cube is "Cado". The mysterious existence Ahakuy Zashounina emerged from Kado and tried to make contact with humans. Shindo, who was absorbed by Kado, accepted the task of mediating between Ahakuy Zashunina and humans. On the other hand, the Japanese government also sent international negotiator Yusara Hana to the scene as a representative. Who is Yahakuy Zashounina? And what is his goal?