The trouble with making movies based on TV series is that there has to be a strong central plot in a movie that also justifies any duplication of what took place in the TV series, be it live-action or animated. But if the central plot is weak enough and only for the sake of having the skits based on the TV series as highlights, then the movie fails.
Cromartie High School, based on the manga by Nonaka Eiji, avoids much of that. It parallels the original story, being about a normal student, Kamiyama Takeshi, who was smart enough to apply to any high school, but went to Cromartie because he wanted to be with friend of his who defended him from punks. Trouble was, his friend was so lacking in the brain department, he failed, leaving Kamiyama amidst a jungle of rowdy students who fight, smoke, and are sans clothes; in a scene that duplicates the manga, a tough named Masa eats an entire stack of pencils Kamiyama spills on his desk.
There are some variations from the manga and anime. Hayashida, he with the wild pink Mohawk hairdo in the original, instead is seen with a kind of ponytail. He is also portrayed as someone who is repeatedly late for class and who is so dumb that his math book is titled "Subtraction for Sillies." And the portrayal of Freddy isn't too much like Freddie Mercury per the manga. OK, he doesn't say a word per the manga Freddie, but a few bouts of singing would've helped. Obviously, Mechazawa, the simplistically designed cylindrical robot with red T-shirt with the characters "konjou" or "guts" is duplicated well enough.
Then there's long-haired preppy-looking Hokuto Takeshi of the Hokuto conglomerate. He wears a white elite high school uniform, clueless that CHS is a municipal school, and proclaims himself student leader. He tries to wriggle out of his dilemma by telling outlandish stories of trying to overthrow his father, the shadow prime minister. Guess what? Kamiyama, Hayashida, Freddy, and the gorilla join him, and they form the Earth Defense Forces, marching through town in khaki uniforms as heroes of justice.
And when Cromartie's toughest thug, Yutaka Takenouchi, gets involved with two hijackers, he is stranded somewhere in South America, captured by a primitive tribe, and set out to be the husband of a b^tt-ugly native woman who looks like Ronnie Corbett from the Two Ronnies, even down to the glasses. His replacement is one of the hijackers, who wears a ski-mask, but the students are too dumb to know that he's an imposter, so he is accepted as Mask de Takenouchi.
The central plot involves the arrival of gorilla-like aliens, Gori and Lla (get it?) who are a nod to the cheesy Japanese sci-fi shows or movies of the 60's and 70's, who want to take over the earth, and do so by enslaving the delinquents. Before long, the shirtless delinquents are sporting antennae headbands and doing exercises and routines that obviously parody the Shaolin kung-fu films.
As for real laughs, there is an Exorcist parody involving Mechazawa who pukes green and even emits the profanities uttered by Linda Blair, as well as the brightly lit doorway scene. And the part where Kamiyama tries to educate his classmates on the dangers of smoking is a highlight, at the expense of Masa and Mechazawa. It shows how delinquents think smoking is cool, but they need something to do with their hands.
Some scenes are duplicated but fail due to the real-life portrayal. The scene of the show Pootan, the surreal comedy of two guys dressed in plush suits, and Noboru Yamaguchi, the Afro-ed punk who tries to figure out why Pootan is popular, seems pointless due to lacking real oomph.
Takamasa Suga is the heart of this movie as the straight-laced Kamiyama, and does a bang-up portrayal of the manga and anime counterpart. Kaneko Noburu as Hokuto does the manga Hokuto pretty good. It helps if you've seen the anime or read the manga, but if not, it might catch you in a silly frame of mind.