After closing a time loop fiasco in The Disappearance of Haruhi Suzumiya (Vol. 5), our protagonist Kyon is ready to start a new year with a blank slate—no time travel, no apocalyptic worries, and maybe some actual peace and quiet with the SOS Brigade, a club comprised of his high school's most extraordinary students. Their leader is Haruhi, a bold, brash girl who doesn't realize that she's actually a powerful goddess whose moods can easily change the balance of the universe.
Just as Kyon starts to get comfortable, he gets a visit from his friend Mikuru. Except this isn't his Mikuru; it's a Mikuru from eight days in the future! Time traveling shenanigans start all over again as Kyon, guided by the future Mikuru, attempts to stop a terrible future from becoming a reality.