Man, this was such an amazing guest feature. Two peak songs back to back. Definitely check this out if you missed that one last year.
Musōka: https://www.youtube.com/watch?v=bHXB9qI2olE&t=2322s
Maware! Setsugetsuka: https://www.youtube.com/watch?v=bHXB9qI2olE&t=2571s

I also highly recommend their cover of Maware! Setsugetsuka, that's one is amazing too:
https://www.youtube.com/watch?v=zWskZx7Lp2Q