Mechazawa Beta, often referred to simply as Beta or Mini Mechazawa, is a small robot and the younger brother of Shinichi Mechazawa. He is physically compact, with a design that makes him easily mistaken for everyday objects such as a tea canister or a beer can. Despite being described as more advanced than his brother, his vocal capability is limited to repeatedly uttering the phrase Meka-ratta. In the context of Cromartie High: The Movie, Beta is a cell phone that accompanies his brother to school and is frequently stepped on, dropped, or otherwise mishandled by the other characters. His presence serves primarily as a source of deadpan visual comedy within the film's surreal, parody-laden atmosphere.

In terms of personality, Beta is passive and largely unexpressive, communicating only through his single repeated utterance. He does not demonstrate independent motivations or a character arc; his role is defined by his relationship with Shinichi. Shinichi is highly protective of Beta, sometimes carrying him around and becoming agitated if anyone lies about Beta's whereabouts. Beta himself does not initiate action but is often the object of others' antics, highlighting the absurdity of the school environment. His notable ability is his resilience, as he endures constant physical mistreatment without apparent damage. Beta appears as a minor supporting character, contributing to the film's chaotic humor through his robotic simplicity and the baffling reactions he elicits from those around him.