Ichizu/Sakayume

Background

In November 2021, Toho revealed that King Gnu would provide the opening theme "Ichizu" for the MAPPA anime film Jujutsu Kaisen 0. The song was first performed on December 1, 2021, at the 2021 FNS Song Festival 1st Night, and its music video premiered on December 10, 2021. Director Taichi Kimura aimed to fuse rock elements into a "sophisticated world." The music video was King Gnu's first not involving director Perimetron. In late December, the staff announced that King Gnu would also provide the ending theme "Sakayume." The two songs were released together on a CD featuring artwork of Yuta Okkotsu, while an alternate Blu-ray featured artwork of Rika Orimoto. Three versions of the single were released: regular, first press limited, and a limited edition containing footage from a November 2020 performance.

"Ichizu" was written by vocalist and guitarist Daiki Tsuneta, who felt pressure to create an "ideal masterpiece" for the audience. The song features a fast sense of gale and rage with chorus and harmony, returning to a rugged melody. "Sakayume" was digitally released as a surprise on December 24, 2021, conveying a sad voice and gentle, rocky melody. Human Tokyo commented that the song may also comment on the characters Satoru Gojo and Suguru Geto, whose stable relationship fell to tragedy. The music video for "Sakayume" was directed by Perimetron's Osrin and released on January 5, 2022.