In an interview with "Famitsu", Kawada related her experience writing the lyrics for "Joint". Kawada said that she was challenged in writing lyrics for the song, since her previous single "Get My Way" was different from her previous singles. Kawada would read the source material of every anime before writing lyrics for its theme songs. She named the song "Joint" because of "Shana II" theme of characters Shana and Yūji Sakai fighting together. In response to comments that the expressions in her voice were very varied, Kawada stated that she simply sings with the music in the way that she most enjoys.