Anime shudaika, anime theme songs, are in medias res and entryway paratexts that serve as industry interpretations of the main text. The standard structure of an anime episode consists of an opening (“OP”) theme song inserted after the first few minutes of the episode, followed by the main animation, an ending (“ED”) theme song, and then a preview for the next episode. Lasting less than two minutes, the animators of these theme song sequences use them to create genre, character, and tone for the viewer in a short period of time. As a result, OPs are often powerful and upbeat and accompanied by colourful, eye-popping visuals that grab the viewer’s attention. Using close-ups, montage, and rapid cuts synced to the music, producers suggest to the viewers how the setting and each character should be interpreted. EDs, in contrast, are often more slow-paced and transition the viewer out of the main story, bringing the episode to a close. OPs and EDs both generate promotional hype, as they are commonly consumed as separate entities from the main animation itself as “anison(g)” (short for “anime song”). Anisong has also become its own genre within the Japanese music scene and accounts for 10% of overall music sales,[i] consistently reaching the top of the Oricon music charts.

Kimetsu no Yaiba (English title: Demon Slayer)’s OP theme song “Gurenge” (Crimson Lotus) by LiSA—an “anisong singer (anison kashu)”—reached #3 on Oricon, #2 on Japan Hot 100, and #1 on Japan Hot Animation. It was also performed by the artist at the 70th Kōhaku Uta Gassen (2019), an annual New Year’s Eve television special produced by public broadcaster NHK. Through LiSA's appearance on “regular” Japanese TV, many viewers encountered the song for the first time as an independent paratext and had their perceptions of the work indirectly shaped. Standing centre stage in a crimson, Taisho-inspired ensemble, LiSA’s powerful vocals accompanied visuals from the original anime which were projected onto a giant screen behind her, creating a colourful, action-packed spectacle. Perhaps, if this marketing was successful, LiSA’s performance even motivated some to view the original anime in which it was featured.

Through external distribution and marketing, anisong becomes an industry-approved package that informs audiences of a pre-determined “canon” interpretation of the anime’s setting and characters, which is reinforced through repetition as songs are streamed online and featured in karaoke collaborations. However, despite a studio’s insistence on a “pre-approved” interpretation of the main text, anisong’s role as an entryway paratext can often lead to alternative modes of interpretation that have nothing to do with the main narrative. Consuming the theme song before the anime may transform it into a completely different entity in the listener’s mind and affect the manner in which they approach the main text, if they approach it at all. In this way, anime theme songs not only contain meaning, they can also generate meaning, making them powerful paratexts.