Tengoku to Jigoku/Saiko na Futari - Season 1

Ayako is an ambitious young police detective whose big break finally comes when she gets the chance to arrest a murder suspect single-handed. But before she can slap on the cuffs, their souls are switched and Ayako finds herself in the body of Haruto, a psychopathic serial killer!

Now Haruto offers Ayako a choice: either turn herself in to the police and spend her life behind bars or help him clear his name. Ayako has no choice but to choose the latter. On Haruto's instructions, she removes evidence of Haruto's crimes from his apartment before the police can search it.

Hideo, Ayako's police buddy, figures out that her soul has been switched with Haruto's. Ayako, in desperation, seeks Hideo's help in stopping Haruto from killing again. Meanwhile, she learns of an ancient legend about the sun and the moon, and she heads to Amami Oshima island in search of a flower that she hopes can restore her soul to her own body. There, she finds an unexpected clue concerning Haruto.

Haruto commits another hideous murder. When she finds out, Ayako is horrified that her body has been used to take a human life. Later, Hideo tells her that he can no longer cooperate with her out of fear of Haruto, and she feels helpless to prevent another murder. Meanwhile, Mitsuo becomes suspicious and tracks down an eyewitness to the crime.

The more Ayako learns about Haruto, the less she understands him. From everything she hears, he's far from being a psychotic serial killer. So is he covering up for someone? Or is he not the murderer after all?

Suspecting an old love letter in Haruto's possession holds a clue to solving the case, Ayako investigates his past to find out who sent it. Meanwhile, Hideo is approached by a man arrested for gambling who wants to make a plea bargain in exchange for information.

Why is Haruto searching through the unidentified bodies in the morgue for a man named Sakuya Azuma? Who is he and what has he got to do with the case? Ayako and Mitsuo are also frantically searching for the same answers.

While the police investigate the scene of another bizarre murder, Haruto heads back to the hospital where Sakuya has been taken. Ayako begins to suspect that Haruto's estranged brother has something to do with the murders.

After falling from an overpass, the state of Ayako's and Haruto's souls remains in doubt… Meanwhile, police close in on Haruto and his fraternal twin, Sakuya, as the prime suspects in the case.

Haruto is arrested. Despite her promise to save him, Ayako can only stand by helplessly while Mitsuo begins his interrogation. Riku is also questioned by police after returning from his trip with Sakuya. Though worried about Ayako, Riku is conflicted about what he should do.