Need help finding a jrock? jpop? song?

the song was abt sex , this guy singing about “key” thats perfectly shaped for his lover’s “keyhole”. might have been ken hirai ? who sung it? i cant even remeber the melody just that the lyrics really made me laugh
Answers

Quentin: Only jPop song with "key" https

Only jPop song with "key" https://www.projecthello.com/momusu/densha.html