Ren'ai Revolution 21 (恋愛レボリューション21; Love Revolution 21) is Morning Musume's 11th single. It was released on December 13, 2000. It sold a total of 1,113,000 copies and peaked at number two on the Oricon Charts. It ranked as the #5 single for 2001.
This single is the last to feature first generation member Nakazawa Yuko before she graduated from Morning Musume to continue her solo career within Hello! Project.
"Ren'ai Revolution 21" was used as Idol wo Sagase! opening theme. "Inspiration!" was used as the image song for NHK’s NHK BS, and along with the title track as the theme song for Saltimbanco’s 2000-2001 tour of Japan. .