"This is the King that you have problems killing? Wait, who do you think I am?! A Kingslayer?!" Gaeru questioned as he took a quick look at Jin's body as well as the armour he was currently wearing.
With his arrival, it has changed into turquoise green armour plates with a Frog Half Mask as well as the broken cape he continued to wear despite the System's insistence to change it to a new one.
With the compilation of the System's data inscribed into the cards created by Moloch, Bam and Boo were hosting Masamune within its core, the two swords wrapped around Gaeru's living weapon to make it easy for Jin's body to hold.
As Masamune had powers unique to itself, all Bam and Boo did was to fuse with it in order to make it bigger. This was only possible with the aid of the Black Sludge Crystals that Jin incidentally created while cultivating.