REJOICE, WG! THE GREAT SAGE OF NU-ADMIRALS IS BACK!!!
well, i can think of 2 interpretations of 'deadly justice': 1) kill anyone who is being 'unjust' 2) be fair yourself or die
but we don't have a reliable translation atm
But with the implied things about his past based on the tattoo, he could have a very dark past related to his justice viewpoint, but I don't believe this turns him into a negative or evil person like Doberman/Onigumo/Saka, where he'd slaughter non-criminals or anything.
but we don't have a reliable translation atm