Tokyo FM
"Endless" debuted on Japanese radio on August 31, 2011, during the Tokyo FM program "School of Lock!". In the first five days, the song received enough radio airplay to reach number 49 on the "Billboard" radio songs sub-chart. The song received its strongest airplay in early October, after "Documentaly"'s release, when it was the fourth most played song on Japanese radio for the week. The strong airplay led "Endless" to reach number eight on the "Billboard" Japan Hot 100 in the same week.