original song: https://youtu.be/gYEeXHFW9t4?si=qCrZtCoijqF9P21w
'Konpei' and 'Kirara' have nurtured their love since middle school and eventually get married. However, on the day of their wedding, Kirara is involved in a car accident and tragically dies. Desperate, Kirara earnestly wishes to a higher power and finds herself meeting Konpei from the past. Thus, a triangular relationship forms between the past Konpei, the past Kirara, and the present Kirara.
And the song that Konpei used to sing to both Kirara is none other than this song.
