Aira Yuuki’s 15th Single “A Promise” Available on October 7, 2021

Written by Ren

9 October 2021

Aira Yuuki’s 15th single “A Promise,” now has a cover art, a tracklist, and a teaser video. This new track is also the ending theme song of The World’s Finest Assassin Gets Reincarnated in Another World as an Aristocrat!

The lead song, “A Promise,” is a melancholic yet warm chillwave ballad that describes the feelings of someone pining for their lover under the moonlight.

It was arranged by Masayuki Hasuo (siraph, ex. School Food Punishment) and opens up new frontiers for him musically. This track will be released ahead of the rest of the album at midnight on October 7, 2021.

The second track is another version of “A Promise” sung by Dia (CV. Reina Ueda), the anime’s heroine. The lyrics perfectly describe the character’s feelings, so it’s a must-listen for fans of the anime!

The third track is “Awkward Love,” which was based on an actual couple. It is a jazzy pop song that describes a clumsy but innocent pair of lovers.

Samples will be available ahead of the release date, so please check them out!

Product Information

“A Promise” by Aira Yuuki
Ending theme of The World’s Finest Assassin Gets Reincarnated in Another World as an Aristocrat

Release date: November 10, 2021
Price: 1,430 JPY (including 10% tax)


  1. A Promise

Lyrics/Composition: Aira Yuuki
Arrangement: Masayuki Hasuo

  1. A Promise (Dia version) (CV: Reina Ueda)

Lyrics/Composition: Aira Yuuki
Arrangement: Masayuki Hasuo

  1. Awkward Love

Lyrics/Composition: Aira Yuuki
Arrangement: Tomoari Taguma (Dream Monster)

  1. A Promise (karaoke track)
  2. Awkward Love (karaoke track)

A full length music video of “A Promise” will premiere on YouTube at 18:00 on October 7! You can enjoy this music video by up-and-coming creator Kano Komori with Yuuki Aira in real time!




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