Who is the fifth signer?

the first real signer head was goodwins brother, remember whenever goodwin had his hand removed and put an metal hand, well he was waiting until yusei and the other signers defeat the dark signers so goodwin would become a dark signer and a signer because his brother cut his signer hand off and become the leader of the dark signers.so goodwin put on his hand and stole every signers mark and become the ultimate god.once yusei, jack and crow defeated him yuseis sign of the tail was replaced with the sign of the head and the tail was given to crow