They were performed by King Gnu, who aimed the theme songs to focus on the chaotic relationship between the leads, Yuta Okkotsu and Rika Orimoto, with "Ichizu" having a strong starting point and "Sakayume" being more melancholic.
[6] In late December before the film's premiere, the staff revealed that King Gnu would also provide the ending theme "Sakayume (逆夢, lit.
[7] An alternate Blu-ray containing several more tracks from the same band was also released on December 29, 2021, instead featuring an artwork of Rika Orimoto, a cursed skeleton that follows Yuta.
[10] The artists added there a fast sense of gale and rage colored with chorus and harmony which carries the main tune that returns to the first rugged melody.
[13][14] According to King Gnu, it conveys a sad voice and a gentle and rocky melody as seen in its refrain a calm background music.
[15] While the focus of the themes is that of Yuta and Rika's relationship, Human Tokyo also commented that there seems to be a commentary on the characters of Satoru Gojo and Suguru Geto.
[16] The music video was directed by the artist "Perimetron's Osrin", who wanted to give the audience a different perspective from the same band It was released on January 5, 2022.
[17] Eriko Ishii mentioned that the single package "is a high-speed rock tune with a lot of words and the other is a moist ballad".
He pointed out and reaffirmed King Gnu's appeal of "coexistence of avant-garde and classic, aristocratic elegance and enthusiasm on the verge of riot.
"[11] Music writer Tsutomu Matsumoto describes it as "a love song that is so fiercely straight and can no longer be considered catastrophic, even if you look back on the long history of J-POP.
Rocking On stated that "Sakayume" does a good job at explaining Yuta and Rika's chaotic relationship based on certain lyrics that focus on the former's predicament regarding his love for the latter.
[25][26] Yuta's Japanese voice actress Megumi Ogata praised both themes,[27] and made a cover of "Sakayume" for the 30th CD soundtrack based on her entire career.