System Rider Meomi
The plates on the living armour shifted as the System Driver activated the card. The flash of deafening white light was simply the System's way of throwing a flashbang against the enemy hoping they would be stopped in their tracks, so the Living Armour Plates had enough time to rearrange themselves.
And for good reason.
With the card's activation, the System was giving permission to fuse Meomi soul's with Jin's body temporarily, causing him to take the backseat while Meomi forcefully entered.
Thus, as odd as it sounded, Jin was now harbouring two souls in his body with Meomi acting as the dominant one. The new living armour also portrayed this temporary change to match Meomi's exterior appearance.
The plates turned orange in colour and from a Panda Half Mask, it turned to become a Cat Half Mask. (A rather stylish version of the werecat's appearance.)