The Metropolitan Police Department Special Unit’s Ryo Kawakubo (Shota Matsuda) is an ace at handling dangerous cases. Together with his colleague, Kuroki (Eiji Okuda) he is called to the Metropolitan Heliport where they meet "Song Shi-Won." The two agents are tasked with transporting Shi-Won safely to the Police Department.

Ryo has a deep secret: He buried his younger brother with his own hands. Shi-Won has lost all memory of the woman he loved, Kana Ayatsuji (Miori Takimoto). After returning to Japan, Kana is caught up in a street crime, but Ryo saves her. The fate connecting these three people slowly begins to unfold. There is another murder.

Shi-Won, who was shot in the head, is delivered to the hospital. Although the surgery was a success, the surgeon discovers that someone else had performed surgery on Shi-Won's brain. Mysterious enemies target Shi-Won. Ryo saves Shi-Won's life, but is confounded as to why Shi-Won is being targeted.

Ryo is informed that Shi-Won wakes up. A surveillance camera catches an image of the criminal. However, Shi-Won has no recollection of the individual. Ryo gets lost in the memories of his deceased brother, Shige. Shi-Won finally begins to piece together the puzzle of the murdered doctors. Ryo heads to the perpetrator's hideout.

Foreign DNA is discovered in Shi-Won's brain, the DNA of Einstein. Honda sends a sample of Shi-Won's brain to Professor Mikoshiba (Kyusaku Shimada), the Japanese authority on Neurology. Several killings occur in Tokyo. The only heir of Korean Daesung electronics is missing, and is believed to be in Japan. Professor Mikoshiba informs Honda of something terrible.

Ever since joining the police force, Ryo had been constantly checking the data of "missing persons" to find his mother who had abandoned him and his younger brother. Does he find her? Now a member of the Special Unit, Shi-Won begins using his hacking skills on a computer. Shi-Won’s memories begin to change as a direct result of having had his brain shot at and operated on in Japan.

To save Shi-Won, Ryo gives him a gas mask. Shi-Won survives and hears Kana's voice on the cell phone. Shi-Won is gradually recovering his memory. Honda and Asada keep digging into Shi-Won's identity, but in the meanwhile a string of terrible mass murders occurs in Tokyo. One of the victims has blue hair just like Shi-Won’s. A message?

Ryo is finally able to meet his mother he had been searching. Ryo's heart grows troubled at the sight of his depraved mother. Meanwhile, Shi-Won finally regains his memory. "I am Lee Min-Joon." Thanks to Risa, he is brought back to the Special Unit. He ultimately finds a video of his own funeral, and, in it, he sees Kana. To help Ryo's mother, Kana seeks help from her father.

The criminal targeting Shi-won since the latter arrived in Japan is shot dead. He has a suspicious surgical scar, similar to Shi-Won’s. What secret does this man hide? Asada investigates Shi-Won's case further by contacting Kishimoto. The muzzle of a gun is once again pointed at Shi-Won! Ryo manages to come to Shi-Won's aid. The criminal is supposed to be dead, so who is the new perpetrator?

Asada and Kishimoto secretly contact Mizuki from the Cabinet Research Office in order to find the connection between Shi-Won and the CIA. Shi-Won finally informs Ryo of his feelings, "I love Kana." Shi-Won finds Kana at her part-time job and tells her how his feelings for her haven't changed. Kana's heart wavers. Ayatsuji tries to convince Kana to become a doctor.

Shi-Won suddenly whisks Kana away before her appointed meeting with Ryo and once again expresses his feelings for her. Asada obtains further information on Shi-Won from Mizuki. All those targeting Shi-Won get traced to the CIA. The Shi-Won case brings the Special Unit into an unprecedented state of chaos. Yet another assassin targeting Shi-Won emerges.

Ryo pulls the trigger on the assassin pursuing Shi-Won. It turns out to be Risa. More abnormalities begin to occur in Shi-Won's brain. Professor Mikoshiba examines Shi-Won, whose memory is now cloudy. Kana begins to worry about Min-Joon. Ryo tells Kana to abandon her involvement with him and Min-Joon. He wants to protect her. Shi-Won is now the CIA's target at every turn.