While out minding his own business in the city Daisuke is attacked by a beast-like mercenary who turns out to be the brother of the guys Daisuke killed in episode 2 and is out for revenge. Daisuke fights him off but in the struggle he loses his silver-bullet necklace that his father gave him and it falls into a sewer drain. This leads Dice and J to explore the Underground. The Underground is another city that exists miles below Judoh, where illegal immigrants and people who hate Judoh live. The Underground is also home to criminals and escaped convicts. While searching for his necklace Dice meets a young girl called Rumie who had bought the necklace from a street vendor. She says she cannot return it, as she does not know Dice well enough. She leads them back to her workplace where a Doctor who specializes in genetic modification works. The doctor had just finished operating on a beat-like man who wants to be stronger. This turns out to be the mercenary from earlier who attacks Dice and J. They are struggling to cope when Boma shows up and helps them in the battle. Boma tells J and Daisuke that “I like you guys” as his reason for helping. Daisuke gets his necklace back from Rumie.