Ayaka and Daichi Miura Unite for Valentine's Day Duet 'Heart Up'

She explains that the title describes how people come out stronger after the experience of falling in love: "The 'heart' experiences love's bittersweet and heartrending sides, and 'up' is like '1 up' [in video games] where you grow and become a new person after going through it all."

Ayaka and Miura performed onstage together for the first time along with rapper <a href="/music/KREVA">KREVA</a> at his 908 FESTIVAL 2017 in September. After the performance, they got together with Kobayashi at a studio with a better idea of how their collaboration would work out, and recorded a demo on the spot.

Miura feels that the structure of the duet also contributes to the theme it depicts. "Our vocals intertwine with each other throughout the song," he explains. "It's particularly apparent in the chorus, where she and I sing slightly different lines. Various emotions intersect as our voices cross each other, so the harmony and song structure are linked to the content."    

Kobayashi, known for his longtime contribution to the works of <a href="/music/Mr-Children">Mr. Children</a> and other popular Japanese acts, is currently adding the final touches to the track. "They're both such incredibly good singers," he says of the recording session, "so I thought that the arrangement should be like a picture drawn with a single stroke. I think we've ended up with a simple yet powerful song."

The CD single will include versions of the song containing only Ayaka's or Miura's vocals. The DVD of the music video will also have options to hear the song with or without their respective vocal parts.