Chapter 78: Instinct
'I always felt it since before meeting Selene.'
In the depths of a dark memory, the image of a black-haired young man beating someone in the slums on a dark evening.
A cheap knife fell to the ground with blood oozing from a deep gash in the young man's arm, yet despite the thug's loss of resistance. The boy continued to hit the thug's face with a twisted smile on his lips.
'From the beginning, there were feelings that would overwhelm me and take over my body when faced with dangerous situations.'
Images of countless fights flew through the young man's mind, school, high school, college, the military, countless fights and moments where his excessive desire to crush the opponent led to dangerous situations and consequences.
'No matter who scolded me, if someone crossed my path or became aggressive... A dark feeling would well up, my mind would become foggy, and then they would be lying on the floor, usually bleeding or quivering.'
CREATORS' THOUGHTS 
TheDragonSlayer
TheDragonSlayer Blue - Celestial/Phyiscal Energy (Aura)
Red - Vermillion/Magic/Spiritual Energy (Mana)
Purple - Soul Power (Aura+Mana)
Black - Undeath Essence/Necromancy (Anti-Life/De-Anima)
White - Holy Power/Divine Essence (Life/Anima) (Tentative for human warriors/Divine Beasts)
So the crystals he will see in the future will roughtly have these types, there might be special ones for pure spirits like fairies and monsters from Celtic folklore.
But generally Red will benefit his vampire side more, Blue his Werewolf/body more and of course the best are purple that boost him in a balanced state.
There were no black crystals in Daiki because he was a failed experiment and didn't die before tranformation!
Black crystals are probably going to be a type that effects his Evil God bloodline and indirectly maybe effect his persona(slightly), however he will suffer and there will be a chance of death due to their Anti-Life energy.
Hope this helps on clarity about the colours!
Gifts
-- Gift
received Weekly Power Status
-- Power
Ranking 
-- Power
stone