Ouroboros (2015)

Both dramas are stories of revenge. The series surrounds the fulfillment of revenge for a beloved person who died violently when the main characters were younger. The stories' conclusions are reminiscent of each other. Ikuta Toma also stars in both dramas.

Both are mystery crime dramas where the lines and the roles between victims, investigators and assaillant/criminals are quite interchangeable and were quite blurred. Both dramas are very intriguing due to the fact you can never quite pinpoint who was it acting as an investigator, who were the victims and who were the true criminals as the truth ended up not being as straightforward as one had initially assumed. Also both dramas had Hirosue Ryoko playing as a victim character who ended up entangled in the many conspiracies in the dramas.

They're both about traumatic pasts and its effect on the main characters. They're both dark and psychologically complex! (love them both)

Both revolve around an old case the main character trying desperately to solve, have many flashbacks about the characters when they were kids, corruption within police, tragedy and Hirosue Ryoko.

They are many similarities between the two drama especially due to its theme and its execution. They both focus on revenge and on what exactly is justice and retribution. Also the ambience and the ending are similar.

Both dramas are about two people who share a dark childhood. The main characters are both a police officer and someone involved in the underworld. In Ouroboros, the mains are secretly working together for revenge while in Kill It they are unaware of their shared past and are on opposite sides of a case.

If you like wonderful mystery dramas, you will like it.

Both are surprising japanese TV dramas with great plot twist in the end.

Main characters are orphans who became best friend like family. To avenge someone they love dearly, they took on new identities: One works in the criminal underworld while the other a business man.

Both japanese dramas are really complex and have a great plot about suspense.

Both men grew up poor orphanage.
They walked separate past.
Their lives intertwined.
Lots of action, tragedy, ….

Those two dramas...taste the same, I should say.

In Ouroboros, two childhood friends choose different paths to avenge a loved one: one a path of light, the other a path of darkness. They are compaired to an Ouroboros, two dragons biting each other's tail, symbol of eternity and harmony of light and darkness.

In Orthros no Inu, two men are connected by a mysterious bond: one is a good man cursed with the power to kill by one touch, the other is a criminal blessed with the power to heal with one touch. They are compared to Orthros Dog, a two faced dog, one good, one evil, bound together by destiny.

Both are about children who witness the cruel death of people they love, and who promise to avenge them once they grow up.

Childhood friends. One became detective. Secret not being told.
Are they still friend after the tragedy.
How do they solve the mystery murder case.

Both have two male leads who have a (somewhat) close relationship but are opposites when it comes to their morals. One character is more involved with the underworld while the other character is a righteous police officer, meaning they butt heads frequently but still work well together.

Both dramas have that same gritty feel to them and are focussed on crime.

Both are dark, mysterious dramas, with plot turning upside-down; great cast, more 'adult dramas'