It became Miporin's first No. 1 hit in almost 3 years since "Midnight Taxi" back in 1990 (all of the hits in between the two songs peaked at No. 3), and broke through the 2-million barrier in sales. The lyrics were written by Nakayama and WANDS vocalist Show Wesugi（上杉昇）with Tetsuro Oda（織田哲郎）taking care of the music. Even with the relatively late release date, "Sekaijuu" managed to become the 37th-ranked song for 1992 but then a year later, it would also become the 10th-ranked song for 1993. The popularity of the song also earned both halves of the duet a ticket to the 1992 Kohaku Utagassen although WANDS wasn't officially listed on the performer slate (their name appeared just like with this phrase in brackets). And for a while at least, "Sekaijuu" was the most successful single by a solo female vocalist.
Another arbiter of a song's success is how often it's been covered. Composer Tetsuro Oda has done his own take on "Sekaijuu" along with other singers like Junichi Inagaki（稲垣潤一）and Hitomi Shimatani（島谷ひとみ）. And even Noriko Sakai（酒井法子）did a cover of the song as an official single in 2007. It would also be her final single to date before those personal problems started to set in.