Dr. Muscle Beetle

From ANN: The manga's story centers on Mamoru Genki, a macho young man who believes in protecting people, but he himself is driven by debt and is forced to commit robbery with a loosely organized crime gang. Mamoru and other gang members rob an insect museum of an old professor, whom he had just met and "protected." Pushed to the limit, Mamoru unleashes the true power of his well-trained body and tries to stick to his ideal of protecting people.