Riddle collars Yuu during his Overblot and now theres a permanent scar that shows where they were almost decapitated.
He can't look them in the eyes some days because the guilt is constantly there, constantly eating at him. He says he likes when they wear turtlenecks and high collared shirts because it makes them look professional and attractive, but in reality its him trying to avoid his guilt.
It never works and he can't help but think he should be the one with ever lasting scars for his crime
I'd imagine each blot gives a different scar.
Riddles is a nasty gash on their neck.
Leonas are crack-like formations from his UM that trail down your neck from Riddles scar and across your shoulders and chest as well.
Azuls encounter gives you a few nasty suction mark shaped scars along your back from where he tried to wring your body apart.
Jamil's scar is from where you were impaled on his projectiles. An entry and exit hole through your abdomen.
Vil's gave you a discoloration in your veins along your stomach and arms, making them black. You look like you've been poisoned.
Idia gave you some awful burn marks all across your back and legs.
I wonder what Malleus has in store for Yuu....