QUITE ODD-Alexander Davis DNA Pendant. When a DNA pendant is commissioned, Davis takes a blood sample from the wearer and their DNA sequence is analysed. The combination of gemstones corresponds to a unique part of their DNA.
SNK // Noragami This. This fits surprisingly well. We've got Yukine/Eren handling the anger management, Hiyori/Mikasa being the cute/confidant scarf-wearer, and I guess. Yato/Levi both have black hair?