Okay, I think this one will be even harder to learn the lyrics for. This also uses imagery with nature that it hard to interpret, so please keep that in mind. For this song, I like where the parts overlap the most.
I'm not really sure why they chose this title, considering how the word “bolero” is supposed to be for slow-tempo Latin dance music and I can't really call this song “slow-tempo”, but anyway, it's a fun song to listen to.
It's just a guess, but I think this song is about the two star-crossed lovers who can only meet once a year on Tanabata. I really enjoyed this song too, even though it's slow paced.