K started as an anime series produced by studio GoHands in conjunction with the writers GoRA back in Fall 2012. The series follows Yashiro Isana, a high school student living in a region an advanced Tokyo Metropolis called Shizume City. Shiro while seemly normal is quickly drawn into a supernatural world led by warring Kings who hold immense power and are followed by loyal clansmen when he is accused of murdering a member of the fearsome Red Clan Homra.
The series swaps between Shiro as he comes to the realization that everything he knows may have been a lie as he tries to prove his innocence to a fearsome swordsman eager to claim his life if he is judged to be evil; Homra as it collapses under the weight of their clansmen's death and their Kings failing strength; and finally The Blue Clan, Scepter 4, a specialized police force working alongside the government to keep order among the clans.
K was followed by a movie, K: Missing Kings that follows the clans introduced during the first season as they recover from the aftermath of those events while facing a new challenge from the Green Clan ≪jungle≫, a clan who runs a vast social media network used to recruit worthy clansmen.
Finally, in late 2015, K returned with a second season K: Return of Kings which seeks to answer questions left unsaid as previously warring clans are forced to cooperate to face a new threat.
K also has a number of novels and manga taking place before or during the series that serve to elaborate on the lives of the characters. There are even drama CDs and short stories written to fill in missing gaps in the K universe.