Yorushika is such a treat and a group that I constantly come back to with all the memories and feeling their song invoke in me. Your evaluations were spot on and you really dont need to know the language or the lyrics to get a feel for what Yorushika wants to convey. Yes Suis is like Aca-ne from Zutomayo who doesn't show their face in public or live performances. Thanks again for checking out some of my requests!
You guess is actually so accurate! These two songs were from Elma's journey finding for Amy(a man) after he left her for unknown reason which she will eventually found through the letters he left. The songs were all connected there are 2 albums dedicated for the story("That's why I gave up on music" on Amy's perspective and then "Elma" on Elma's perspective)
Yorushika (both the Singer "Suis" and the producer "N-Buna" are actually known for not showing their face or any other irl info. This has somewhat been a trend among japanese artists for some time. Another big name who does it is Ado, who also does godly live shows.
If you got interested in Japanese music, I’d be grateful of you react to Idol by YOASOBI as well. They are not a widely known international music group!