K (also called K Project) is a 2012 anime series animated by the studio GoHands and directed by Shingo Suzuki, who also serves as character designer for the series. It began airing on MBS on October 5, 2012. The anime has been licensed by Viz Media in North America and by Madman Entertainment in Australia.

A manga prequel called K: Memory of Red, drawn by Yui Kuroe was serialized in Kodansha's Aria between May 28, 2012 and August 15, 2013. Another prequel manga, K: Stray Dog Story, ran in Kodansha's good! Afternoon between November 2012 and March 2013. A third manga K: Days of Blue, was serialized in Kodansha's Aria between November 2013 and July 2014, and a fourth, K: Countdown, ran in Aria from December 2014 to July 2015, while a fifth, K: Missing Kings, ran in Monthly G Fantasy from April to August 2015. Five more manga series; K: The First, Gakuen K, K: Lost small world, K: Dream of Green, and K: Return of Kings, are also still ongoing. Furthermore, two light novels, called K Side:Blue and K Side:Red, were released in October and November 2012. A third light novel called K Side:Black and white was released in May 2013 and another one, K - Lost small world was released in April 2014.

A sequel film was released on July 12, 2014. A visual novel is also in development by Otomate.

A sequel anime project was announced on the official Twitter account of the series. The new anime series, K: Return of Kings, aired from October 3, 2015 to December 26, 2015, rounding up the anime series and delivering its ending.

A new anime project featuring an original story by GoRA and GoHands, titled K: Seven Stories, has been green-lit. GoHands and Shingo Suzuki are returning to produce and direct the anime, respectively.