25 years ago, Kotone Togashi (Nanaha Itose), a female college student from Hatano Town, disappeared, leaving only her severed finger behind. Time passes with the case remaining unsolved, and Kotone's older brother Hiroyuki Togashi (Akira Yasuda) is currently working as a detective in the Life Safety Division of Hatano Police Station. Masato Yashiro (Koji Mizukami), a career police officer who has been transferred to the police station, suspects that Togashi killed Kotone, but one day, the body of a woman without fingers is discovered. After 25 years, the "monster" begins to move again.
What was found in the reed fields was the body of a woman that Masato had been using in a decoy investigation. Masato's father, Masayoshi Yashiro (Atsuro Watabe), a deputy commissioner of the National Police Agency, learns of this and plans to cover it up, fearing that it will hinder his career advancement. Meanwhile, Togashi learns that Yanagi's (Shinya Kote) only daughter Mio (Fumiori Kubo) has not returned home for the past few days, and finds Mio passed out drunk in the downtown area and takes her into custody. However, that night, another terrible incident occurs...
The culprit who lined up Mio's fingers in front of Yanagi's liquor store was Togashi. However, Togashi is interviewed by Shoko (Mahi Sei) as a witness with an indifferent look on her face. Masato, who was present at the hearing, expresses his distrust of Togashi on the spot, and the two deepen their conflict. After that, Togashi continues to display inexplicable behavior to those around him, and even his old friends Shoko and Tadokoro (Shingo Fujimori) begin to suspect Togashi of having committed the crime. What is Togashi hiding? Is Mio alive? Is that the monster, or is it me?
Masato grows suspicious of Togashi's unnatural statement and suspects that Togashi cut off Mio's finger at Rinko's (Ayame Goriki) yakiniku restaurant, but Togashi is later released based on Tadokoro's testimony. Meanwhile, Kayo (Junko Takahata) and Nakahashi (Jun Hashimoto) rely on Yashiro, a familiar face, to proceed with the redevelopment of Hatano Town. Furthermore, the willow in the middle of the whirlpool is used for a redevelopment event, and the togashi tree, which has become extremely popular, invades the site. Hatano Town is thrown into turmoil as a mysterious murder case and a redevelopment plot intertwine.
“Dad, please let me out.” What does the sudden email from Mio mean? The events of the night Mio disappeared come back to Togashi's mind, and the truth behind the disappearance becomes clear. "We have to catch him." Togashi also decides to become a "monster". On the other hand, Masato also discovers the truth hidden in Mio's email and questions Togashi. Meanwhile, the “monster” finally begins to move!
Mio's body is discovered in Yanagi's shop, and the true identity of the "monster" is finally revealed. Yanagi, who was detained, tells the story of what happened up until now, but is it really true? Togashi and Masato realize that Mio's mother, Harumi, is deeply involved behind Yanagi's madness, and begin to shake Yanagi. Kotone's body has not yet been found, and Yanagi is being interrogated, but the tense battle takes an unexpected turn. "I returned Kotone to you."
Hatano police station is in an uproar over Yanagi's sudden death. It turns out that someone led Yanagi to commit suicide, suggesting that the incident is not over yet. As Rinko's testimony arouses new suspicions, Togashi follows Yanagi's words and continues searching for his sister's body. As a result, skeletal corpses are discovered one after another on Nakahashi's private property, but none of them appear to be Kotone. But then, a word from Togashi's mother, Noriko, leads Togashi to the shocking truth that has been hidden for 25 years.
The death of Akiyama, the current police chief, shakes Hatano Town once again. Believing that there may have been some kind of deal between the murdered Akiyama and Kayo, Togashi and Masato use the conversation between Tadokoro and Kayo as clues and uncover another truth behind Yanagi's crime. Tadokoro, who holds the key to the case, is questioned by Togashi and as a result regains his lost memories from 25 years ago, but after that, even more shocking facts are revealed.
25 years ago, Masayoshi buried his crimes in the dark, and now he is within reach of his great ambition to become the Commissioner of the National Police Agency. As a result of interrogating Tadokoro, Togashi comes to the conclusion that there is a real culprit who hit and killed Kotone, and because of his connection with Nakahashi, he begins to suspect that the real culprit is Masayoshi. Meanwhile, Masato is informed of Masayoshi's suspicions, and remembers that Masayoshi once abandoned his mother, and decides to confront Masayoshi. The drama between Masayoshi and Masato, father and son is finally reaching its final stage!
Masato learns the true nature of justice and the truth behind Kotone's death, and confesses the truth to Togashi. Togashi calms down Masato, who is trying to settle the matter on his own, and sets out with Moridaira, Shoko, and others to finally solve the case. The group tries to find out the truth from Nakahashi and Kayo, who have ties to justice, but... When the hidden truth comes to light, Togashi and Masato are forced to make a mutual decision. The "monster" that nests in people's hearts -- what is the outcome that awaits when its true identity is exposed?
Complete episode guide for Monster with detailed information about every season and episode including air dates, summaries, ratings, and streaming availability in United States.
This episode guide is organized by seasons, making it easy to track your viewing progress or find specific episodes. Use the episode information to plan your binge-watching sessions or catch up on missed episodes.