It seems that two different people have sung this song, here’s what I’ve found, these two seem to be different:
Apparently two people, Nayuta and LeeYeon, sang this song. People in the comments on the videos cannot agree who sang which, and I would like to know where I could hear more of their work.
Is one of these official?
For that matter, are even the lyrics official? Did this play in the game?
I think the first one is sung by LeeYeon, while the second is a mix of both LeeYeon and Nayuta, the version featured in dai’s album “Umaretekite Kurete Arigatou” is sung by Nayuta, here it is: