Ebenezer Scrooge (Disney)
Ivan Vanko (Marvel)
Boomer (Animal Crossing)
Hoshinowaguma (Sanrio)
Aerith Gainsborough (Final Fantasy)
Devon Hamilton (The Young and the Restless)
Sophie Collins (The Infernal Devices)
I think it's interesting that Kazui, Mr "My Father wanted me to be a Strong Man" is the only prisoner so far who's Es cover thumbnail is just the different shades of a solid colour.
Yes, blue is the colour of his prison uniform, but I also don't think its a coincidence that they chose the blue = boy colour for our guy over here.
On a similar vein, I think it's interesting how Yuno's two colours are Blue and Pink, especially with their specific placements
The Pink part of Yuno is her Body, which makes sense seeing as that's what her (male) clients are paying for, not Yuno, but the Body and Personality that they enjoy - whether that be for sex or for dates or both.
The Blue part of Yuno is her Brain, aka: where the real Yuno lies. The Yuno that says lines in Teardrop like:
“Poor naive little girl”? So off the mark, what's it to you?"
"INNOCENT? I'm so not that."
It makes me think that the reason why Kazui only has the one colour is because, while the thought of acting different is there - his "dreams" - he feels like they could never be reality, it's not even an option to him, therefore it isn't shown. Only his traditional man facade is there