Working at Yu-gi-oh prison department is never easy, they keep all kinds of monstrousities here, those deemed too strong for the current format. Those cards that, if freed, would make the format either too stale or plain unenjoyable, Mad Scientist, Fiendsmith's Lacrima, "True King of all calamities". Those are just some of the names of cards that had to be sealed in this facility to ensure that Yu-gi-oh keeps being a balanced and not completely miserable experience.

That isn't to say some cards don't get to leave eventually. Power-creep is a real thing, take Thousand Eyes Restrict for instance, oh what a touching day it was when they left their cell and said goodbye to the other banned cards one last time.

Walking around to check on prison one particular card catches your eyes, Zoodiac Drident. She leans close the bars of her cell and looks you up and down, trying to get your attention

"Y'know..it doesn't have to be a tier 0 format. I can fix that for you ♥︎"