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. This edition includes the message song "All is well -Re:8EST edition-" written by Kanjani8 and composed by Shota Yasuda, and comes with a DVD including "Kassai" Music Clip & Solo Angle, "CIRCLE" Music Clip (1half size), "All is well -Re:8EST edition-" Music Clip and each making. A lyrics photo booklet (16 pages) is enclosed.