'''Go For It! Manzai Grand Prix!' (めざせM-1グランプリ Mezase M-1 guranpuri; alternatively: めざせお笑いグランプリ Mezase owarai guranpuri) is the fifth Black Lagoon'' omake. It was originally released in the fifth manga volume on March 17, 2006, and it was later animated and released on the seventh Japanese Blu-ray disk on March 25, 2010.

At her high school, Yukio Washimine tells her friends that this year's performance for the school festival will be manzai (Japanese stand-up comedy). When Maki recalls that Yukio is graduating, Yukio cuts her off and advises her to ignore the finer details. To Maki's side, Mami and Yoshi indifferently remark that they do not care about the idea. Smiling, Yukio calls for them to rehearse and tells Maki to come to her place. At Yukio's house, the two girls rehearse an act involving Idi Amin, which confuses Maki. Seeing Yukio's stern look, Maki apologizes and is forgiven by her, but Ginji Matsuzaki appears, much to the latter girl's horror. Ginji glares at Maki and informs her that phrases like "never mind" from Yukio indicate deathly concern, saying that Yukio's demeanor makes her sleepless and crazy. Assuring Maki that they will be fine, he proclaims that they will fulfill Yukio's wishes. As Maki panics and shivers, Ginji remarks that Bandō and Yoshida grew up watching manzai, shouting for the two to come out and demonstrate.

Standing with serious demeanors, Yoshida and Bandō introduce themselves, with the latter saying that the world is full of cruel people. Yoshida asks him what he means by that, so Bandō elaborates that a punk scratched his Benz with a ten yen coin when he was making a collection run. When Yoshida expresses that the punk needs to be disciplined, Bandō wholeheartedly agrees and recalls that he asked the kid if he knew how much his Benz costs. He then showed the boy a 500 yen coin and told the kid to use that instead if he was going to scratch the car, but Bandō is interrupted by Yoshida punching him and berating him for letting the child do that, surprising Maki. Angered, Bandō pulls out steel knuckles and asks Yoshida why he hit his senior yakuza, hitting him back. Watching the spectacle, Ginji and Yukio laugh at the act whereas Maki remains distraught. Looking at Maki, Yukio smiles and asks Maki if she enjoyed the act. Seeing her smiling and armed with the steel knuckles, Maki believes that she has to kill Yukio first or else she will be killed.

Later, Yoshi sees a crowd and ambulance outside the Washimine residence and wonders what is going on. Mami informs her that Maki grabbed a crowbar in the middle of her routine for some reason and beat Yukio, resulting in the yakuza pulling out weapons. An unconscious Yukio is moved into an ambulance on a stretcher while Ginji, Yoshida, Bandō, and Maki are escorted in handcuffs by a police officer. Meanwhile, Balalaika and Revy, dressed in ponchos and sombreros, tell Rock that they will be a manzai trio called "Trio Los Panchos," but Rock quietly declines without hesitation.