Thanks for sharing that, I didn't know Omoi was finally available on Spotify! It was originally released at her 15th anniversary live on October 28th but it wasn't uploaded for a while afterwards, I think (I didn't think it was going to be on Spotify at all after a while). Omoi was actually an unreleased song originally written in the mid-2000s,
as Nana shared when they announced this single release, so that's why she's already performed it live before.
(I also learned today that the writer of both songs, Susumu Nishikawa, has worked with her several times in the past, including for her debut single!)
I like Omoi, it's a solid rock ballad, the song is beautiful and Nana sounds great! The End of Darkness is nice too, but nothing too memorable.