Yes, almost forgot, since we're having such a conversation – on Thursday, I read about "souls."
White – a healthy soul, the so-called "standard" without any defects.
Gray – a wounded soul; it can manifest in traits such as pettiness, envy, melancholy, lack of independence, inability to think for oneself, etc.
Black – a sick soul; people with such a soul are usually burdened with very dark thoughts. These can be both cruel murderers and individuals prone to severe depression.
Gold – this color belongs to people with a very "great" soul, those who are destined for a great fate or who have the potential for it. This can be either a competent and beloved king or, for example, a selfless head of an orphanage. At the same time, such a person may possess almost any character traits and is not necessarily "good." Gold can be not only a popular king but also a cruel despot.
Red – the color of demons or those possessed by them.
Blue – the color of any undead.
Purple – the color of celestials.
Green – the color of summoned creatures.
Pink – the color of gods, demigods, saints, and other beings that stand above ordinary mortals.
Aiyano gains the ability to see the color of souls without wearing a mask.