'''Viva! Youth!' (ビバ！ヤング編 Biba! Yangu hen) is the seventh Black Lagoon'' omake. It was originally released in the seventh manga volume on October 19, 2007, and it was later animated and released on the sixth Japanese Blu-ray disk on February 24, 2010.

Waking up as a 13-year-old boy, Rock complains about the story change. As he claims that he can try to get used to it, a 14-year-old Revy barges into the door. Rock is surprised at her appearance, but Revy retorts that his haircut is bad too. Although he tries to sneak away, the two pirates see an embarrassed 12-year-old Benny with braces and a dorky outfit. Holding his hands up, Benny tells them to stop looking and exclaims that is why he did not want them to see him. Revy wonders where Dutch is, and Benny explains that he already found out and ran away from everyone's sight. Nearby, a skinny blonde woman in expensive clothing informs the three children that she has not seen Dutch nearby. When they ask her who she is, she says that she is a 29-year-old Yolanda, surprising the children. The young nun comments that Eda has an interesting look but has not seen her around. Hiding nearby, a 17-year-old Eda pants while in a cheerleader uniform.

Going to Balalaika's house, Rock and Revy meet a 9-year-old Balalaika, who innocently claims that she has no idea what is going on and that her mother and father are not present. Revy and Rock stand awkwardly, with the former remarking that she cannot be further surprised after seeing Yolanda's transformation. The young Balalaika replies that Revy's eyes are scary and laughs, annoying the latter. Noticing the three nearby, a 15-year-old Chang sees that they have turned into children too. Revy sees the 22-year-old Bao and is surprised at the 12-year-old Shenhua, who orders Revy to mind her business. When Balalaika comments that she has not seen her sergeant anywhere, a 16-year-old, skinny boy appears and calls for the captain, much to their shock. The boy is surprised that she does not recognize him as Boris, surprising the three children even more. Boris confesses that he joined a military academy to toughen up after being teased by children for his scrawny build. Staring at him in complete shock, the three children unanimously agree that Boris should have remained a skinny child.