Sooooo

Frog was a king too, but his kingdom fell prior to getting isekaid (i think) so he became a rogue and wanders around but becoming a rogue king with a fallen kingdom had both pros and cons, the con is his body degrading into a lower state/level (he’s originally a lizard/monster type as shown) and the pros meant he gained exclusive unique powers as a rogue king which is part of the game

Oh! Cool!
I just thought that he was a cute NPC that got attached to the MC. Hehe, thank you for the info!