thanks to aska's hit solo single " (hajimari wa itsumo ame)" in 1991 and several powerful tieups with tv programs, their popularity peaked during the first half of the 1990s. in those days, they released five million-selling hits: "say yes" and "if", "yah yah yah/ (yah yah yah/yume no bannin)", "heart/natural/on your mark", " (meguriai)". "say yes" and "yah yah yah" each sold over two million copies. "say yes", released in 1991, is the sixth best-selling single in japanese oricon charts history. "say yes" was the opening theme song for " (101st proposal)", a 1991 tv drama. their album "tree" has been certified by the riaj for sales of 3 million copies. their two subsequent albums, "guys" (1992) and "red hill" (1993), were certified for a million each.