A corpse of a clown is found in a park. Detective Shirataka Amane of Musashino Higashi Police Station begins investigating with rookie detective Uzuka Shinsaku. They find a picture of the victim holding a balloon with the number 1 and the letters TTX on social media which indicates pufferfish poisoning. Shirataka intuitively suspects that this is an incriminating statement done by a serial killer, but Chief Investigator Fukukawa Saeko denies her. Detective Kusano Seiya and other personnel of MPD First Investigative Division join the investigation, then a second murder occurs. Shirataka recalls an unsolved kidnapping and murder case from two years ago that she still regrets.
we follow forensic scientist Higa Mika as she struggles to step out of Professor Asakawa Toru's shadow and become an independent scientist. For some reason, it seems that she's stuck being his assistant and can't progress any further, when a female junior high school student gets strangled in the jurisdiction of the Nishihara Police Station.
It’s the mid-1970s at a time before the TV recording function became commonplace. The Kaijuu Club is a group of youths that loves fancy special effects series such as Ultraman and Ultra Seven. They put everything into researching monsters which appear in these series from every possible angle and hold editorial meetings to publish a fan magazine on the monsters. The members of the club would gather at their usual coffee shop and have enthusiastic and heated discussions without being daunted by the chilly stares of the people around them.