The 47th single "Kassai" by Kanjani8, which marks the 18th anniversary of their debut in 2022, is an advance single released prior to the "18 Sai" summer festival of Kanjani8. It also includes "CIRCLE", which was performed in March as the theme song for the joint project of the Japan Pavilion at the Dubai Expo & Kanjani8. Regular edition includes a new song "Seishun FIREWORKS" as a B-side track. Also includes "Aopanna -Re:8EST edition-" and "Yellow Pansy Street -Re:8EST edition-" as "Re:8EST" project. A 3-sided 6-page lyric card is enclosed.