On October 5, 2016, 星野源 (Gen Hoshino) released his ninth single, 「恋」 (Koi). Six days later, TBS began broadcasting Nigeru wa Haji da ga Yaku ni Tatsu, with Hoshino playing Tsuzaki Hiramasa alongside Aragaki Yui.
Koi was the drama’s theme song. Its ending sequence, choreographed by MIKIKO, soon became known as the Koi Dance and spread far beyond the series itself.
That success can make it easy to remember the dance before the music. Hoshino’s own account of how he created Koi puts the song back first.
Finding the right speed
When Koi was released, Hoshino explained that he had considered several approaches while writing it, including disco, jump blues, soul and jazz.
None gave him what he wanted.
He was looking for music that would make him want to move, but the usual vocabulary of dance music felt too familiar. He initially worked around 120 to 130 BPM, a tempo he regarded as particularly suitable for dancing, without finding the excitement he was after.
He kept increasing the tempo in his head.
Around 160 BPM, the idea worked.
Hoshino called the result “Motown-core”. He imagined a Motown record made to be played at 33 rpm accidentally spinning at 45. At that speed, the dance beat stopped sounding like the kind of dance music he had initially been trying to avoid.
The description is unusually concrete. Koi did not begin with the choreography that later made it famous. Hoshino was already thinking about physical movement while constructing the song itself.
He was also continuing ideas developed around YELLOW DANCER, released the previous year. Hoshino had been using the term “Yellow Music” for his approach to combining influences from Black American music with his own understanding of Japanese pop. With Koi, he wanted that identity to work without requiring an explanation from him.
The Koi Dance
Nigeru wa Haji da ga Yaku ni Tatsu gave that music a highly visible form.
MIKIKO choreographed both the Koi music video and the dance used during the drama’s ending sequence. Hoshino later explained that the television choreography had not been simplified in anticipation of viewers copying it. The production kept the dance because they found it interesting.
Viewers copied it anyway.
TBS was already reporting extraordinary interest only three days after the first episode, noting that the dance video had passed one million views in a single day.
The association became difficult to separate. Koi and the dance were circulating together only weeks after the single had been released.
A 2016 song that dominated 2017
The drama ended in December 2016. Koi did not disappear with it.
Its longer trajectory is particularly clear in the Billboard Japan Hot 100.
Koi finished 2017 as the chart’s No. 1 song of the year.
Billboard Japan reported that it led five individual metrics during 2017: radio airplay, downloads, look-ups, Twitter and video views. The song had already spent five weeks at No. 1 on the weekly Hot 100 during 2016 and added another six in 2017.
For a single released in October 2016, that second year matters. The television series had ended, but Koi was still circulating through radio, downloads, video and streaming.
The tenth anniversary has also brought the song back to a physical format. On October 5, Hoshino announced a limited 7-inch edition of Koi for January 28, 2027, his 46th birthday. “Continues,” originally included on the 2016 single, appears on the B-side. Both tracks have been newly remastered for the release under Hoshino’s supervision.
Ten years later, Hoshino’s description from 2016 remains a useful way to hear it: a Motown record spinning too fast.
Sources
Gen Hoshino official website, *Koi* discography entry
Real Sound, interview with Gen Hoshino on the creation of Koi, October 2016
TBS, *Nigeru wa Haji da ga Yaku ni Tatsu*, production report on the Koi Dance, October 2016
Billboard Japan, 2017 Year-End Hot 100 and report on Koi’s chart performance
Billboard Japan, Gen Hoshino announces Koi 10th anniversary 7-inch edition, October 2026