Black energy.
Looking into his memories, it wasn’t always the case that my future self used the black energy from the start.
The color of energy varies from person to person, and it blooms in many different ways depending on the nature of the energy contained within it.
However, future me, who devoured others' abilities, changed colors with each phase.
At first, it was achromatic.
After consuming the World Tree, the most intense color was green, full of vibrant life force, and each time he absorbed more power, it would shine with a dazzling rainbow color.
The moment it turned completely black was after
