Original song:    • coldrain - MAYDAY feat. Ryo from Crys...  
AmaLee ver.:    • Fire Force - "Mayday" (FULL Opening) ...  
Ike/Hayato ver.:    • MAYDAY / coldrain【加賀美ハヤト × Ike Evelan...  

Got introduced to Mayday from Ike & Hayato's cover, which was awesome. As soon as I found out AmaLee also covered the song, I had to combine them.
The three vocalists balance each other out nicely: AmaLee's part is purely clean singing, Hayato's is mostly growls, and Ike is a mix of both. All of them do an absolutely stellar job with their respective performances.
Since no official instrumental for Mayday yet exists, I had to make one myself. Couldn't help but throw in a little guitar solo in there. (I played the intro wrong, but I didn't notice until after it was finished. Whoops...)

Art sources:
AmaLee - https://shop.leeandlie.com/collection...
Ike/Hayato -   / 1589187507652292608