I did hear what you mean a couple times, but I think it’s either Japanese or Latin. I say Latin because this song actually takes inspiration from old Gregorian chants, and specifically the Dies Irea. There’s a great video about the topic by Kyle Robes (link here: kzbin.info/www/bejne/Y3_Ge32oq7qIeLMsi=ue8qUWrGpwQBmqZx) if you care to learn more about it Along with kinda hearing “Subaru” I also hear “Suba” which makes me think it’s a different language lyrics. Although it would be funny if Rem’s theme is even fawning over Subaru lol. I’d also buy that xd