After teenager Ichigo Kurosaki acquires superpowers from wounded soul reaper Rukia Kuchiki, the two of them join forces to round up lost souls.

Ichigo Kurosaki's school is attacked by strange spirits called Unforgiven (Togabito), revealed to have escaped from Hell, and Rukia Kuchiki and Renji Abarai are sent to investigate. Ichigo's family is targeted by the Unforgiven, who are led by Shuren, and Ichigo's younger sister Yuzu Kurosaki is abducted. An Unforgiven named Kokut? saves Karin Kurosaki from being abducted as well, and convinces Ichigo to accompany him and the Soul Reapers to Hell to save her. When they are attacked by monsters called Kushan?da, the guardians of Hell, on the journey, Ichigo's Hollow mask begins to spontaneously manifest. Kokut? warns him to avoid using his mask lest he lose control and hollowfy entirely, and tells him that the Kushan?da torture Unforgiven for their sins by killing them, as Unforgiven continuously revive, and that spirits killed in Hell become Unforgiven themselves.

It is mid-december, and SOS Brigade chief Haruhi Suzumiya announces that the Brigade is going to hold a Christmas party in their clubroom, with Japanese hotpot for dinner. The brigade members Kyon, Yuki Nagato, Mikuru Asahina and Itsuki Koizumi start preparing everything for the party, such as costumes and decorations. But a couple of days later, Kyon arrives at school only to find that Haruhi is missing. Not only that, but Mikuru claims she has never known Kyon before, Koizumi is also missing, and Yuki has become the sole member of the literature club. The SOS Brigade seems to have never existed, nor has Haruhi Suzumiya. No one in the school has ever heard about her… except for Kyon.