At some point, KOROSHI signs to Eternal
V: Shuri (殊璃) G: Shin (慎) B: Aika (あいか) D: Rouji
At some point, Guitarist Yui joins, and Aika and Shin switch places. Also, Aika changes his name to Kento
V: Shuri (殊璃) G: Yui (萸威) G: Kento (絢斗) B: Shin (慎) D: Rouji
Koroshi disbands, but then immediately revives as Cuartet, and transfers over to Climax Enterprise. Shuri changes his name to Saki, Kento changes his name back to Aika, and Yui changes his name to Riku
Guitarist Riku leaves the band (It is unknown when he left, but he is not present in the Koishigure PV, but he is present at the Ichikawa CLUB GIO live)
V: Saki (咲) G: Aika (鴉嘩) G: RIKU B: Shinkichi (慎吉) D: Rouji
Cuartet begins official activities and holds their first live at Meguro ROCKMAYKAN, which would be deemed their "Home Venue"
Cuartet holds first sponsored live
Cuartet holds a free live at Meguro THE LIVE STATION. Despite the charge being free, the live was deemed "Sold out" because the venue hit capacity.
Drummer Rouji secedes.
Drummer Yousei (悠生) and guitarist Mayoi (真宵) joins
V: Saki (咲) G: Aika (鴉嘩) G: Mayoi (真宵) B: 慎吉 (Shinkichi) D: Yousei (悠生)
At some point, drummer Yousei (悠生) secedes. It can be assumed that support drummer Ashi (Prime A Dees) joined at the same time.
V: Saki (咲) G: Aika (鴉嘩) G: Mayoi (真宵) B: 慎吉 (Shinkichi)
At some point in mid 2004, drummer Junna (准那) joins. (He is featured on the SCANDAL FILE DVD as well as the Imperial omnibus, so it's best assumed he joined some time before June)
V: Saki (咲) G: Aika (鴉嘩) G: Mayoi (真宵) B: 慎吉 (Shinkichi) D: Junna (准那)
At some point before disbanding, guitarist Mayoi (真宵) leaves.
Cuartet temporarily revives for the 『Cuartet Familyの皆様へ~暑中お見舞い申し上げます~』 (Cuartet Family no Minasama e ~shochūomimaimōshiagemasu~) tour.
Cuartet holds one day revival at Meguro ROCKMAYKAN titled "-ONE-MAN OF LIMIT NIGHT- LAST MESSAGE~青春の唄~" and releases a live limited single