It's been a year since the disappearance of Shiro, the Silver King; Kurou Yatogami and Neko have been diligent in their search, but to no end. Their investigation leads to a run-in with members of the now disbanded Red Clan HOMRA—Rikio Kamamoto and Anna Kushina—being pursued by the Green Clan, who desire Anna's powers for their own ends. Now, the members of Scepter 4 are called upon alongside Kurou and Neko in order to rescue Anna, the mascot, and only female member of the ruined Red Clan, from the enemy's clutches and hopefully find Shiro using the young girl's powers. Amidst crisis, the group is forced into a power struggle when the Green Clan threatens to overtake the Gold King's domain. The second step in the K Project series, K: Missing Kings, continues the story of a young boy caught up in a psychic war between seven kings, and showcases each character's struggles after the losses of their respective Kings.

It is the new year, which means that the senior members of the Light Music Club are now third-years, with Azusa Nakano being the only second-year. The seniors soon realize that Azusa will be the only member left once they graduate and decide to recruit new members. Despite trying many methods of attracting underclassmen—handing out fliers, bringing people into the clubroom, and performing at the welcoming ceremony—there are no signs of anyone that plans to join. While heading to the clubroom, Azusa overhears Yui Hirasawa say that the club is fine with only five people and that they can do many fun things together. Changing her mind, she decides that they do not need to recruit any members for the time being. K-On!! revolves around the members of the Light Music Club as they experience their daily high school life. From rehearsing for concerts to just messing around, they are ready to make their last year together an exciting one!

Kings are individuals who have been bestowed with incredible supernatural powers and granted the ability to recruit others into their clans. Protecting the lives and honor of their clansmen is an integral part of the Kings' duties. After a video depicting the heinous murder of a Red Clansman spreads virally, the unassuming student Yashiro Isana is accused of homicide. Now, a manhunt is underway for his head, bringing him into contact with the infamous Black Dog Kurou Yatogami—a skilled swordsman and martial artist determined to follow the wishes of his late master, the Seventh King. Meanwhile, the current Red King, Mikoto Suou, faces his own imminent demise as the search for Yashiro narrows. But during Yashiro's struggle to prove his innocence, a greater conspiracy is unraveling behind the scenes; clouds begin to appear in his memory, and close friends start to question his very existence. What began as a simple murder is now leading towards a full blown war between Kings with the very fate of the world at stake.

Tensions are running high among the clans as the Green King begins making moves that threaten to drive the world into pandemonium. Following the death of the Gold King, the safety of the Dresden Slate, the source of power of the Kings, is under threat. Nagare Hisui, the sly and mysterious leader of the Green Clan Jungle, is determined to procure the powerful Slate by any means possible. Standing directly in his way is Sceptre 4, the Blue Clan, headed by their unyielding King, Reishi Munakata. However, the grim sight of his crumbling Sword of Damocles leaves the stability of his clan and all of Japan in jeopardy. Meanwhile, still recovering from their tragic losses, Anna Kushina and her aggressive clan HOMRA find themselves caught up in the Green King's games. Amidst the chaos, Kurou Yatogami and Neko are left vulnerable while their beloved friend, Yashiro Isana, the Silver King, remains missing. As the remaining clans struggle against the Green King's formidable forces, one final king appears.