When Burai finally overcomes his vengeful feelings and seeing Geki finally embrace his brother with the love he wanted to shrine him with all along.
Just about everything involving Grifforzer and Lamie.
There is some heartwarming things about the Burai's death arc. In the beginning of the arc, Burai had a nightmare that he's been taken to the underworld by a sinister Grim Reaper figure, but along the way, he saw one lonely boy sitting on a bench, implying that he's next after Burai. At that point, Burai begs to the Grim Reaper to stop not for his sake, but for the boy's sake. Then he wakes up. Turns out, the boy was someone still living and very sick. Burai then used his remaining time to help him out and protect him, and even tells his allies to give the life-saving water for the boy. Then it turns out, the same dream happened for real, but the Grim Reaper is instead more benevolent despite looking and sounding scary, and when Burai looked at the bench, the boy's gone. This satisfies Burai that his death at least has a meaning and he sacrificed his life for a good cause.