OH NO
I just finally got to listen to that background vocal that i'm so curious as to what it's spelling.
"Seishun Mannnaka. S-e-i-s-y-u-n"

But wow, they sound pretty good in that.

(The instrumental scares me)
Can't wait for more, they're improving tremendously fast.
This is why I love H!P. :3
(editted because "sy" is not wrong, just not as common in the Hepburn system.)