Mr. Belt is the name given to the Drive Driver's artificial intelligence by Shinnosuke, who serves as the navigation system for the Tridoron and is the one to summon the Shift Cars for Kamen Rider Drive. Mr. Belt was originally Krim Steinbelt, a scientist who created the system known as Core Driviars (コアドライビア Koa Doraibia) for the Shift Cars and Tridoron. However, after he gave Core Driviars to his colleague Professor Banno, the man used them to create the Roidmudes, resulting in Steinbelt's death at their hands. He had originally planned on implanting his memories into the robot Cyberoid ZZZ, but ultimately decided on the Drive Driver. During the Global Freeze, Mr. Belt worked with the android Proto Zero to fight the Roidmudes as Proto Drive, until Proto Zero's apparent death. In the ensuing time, Mr. Belt upgraded the Kamen Rider Drive arsenal to its current state when Shinnosuke finds him. He chooses the young man to be Kamen Rider Drive because of his nature to act first without any hesitation. With the proper guidance and advice, Shinnosuke's personality would be a major force in future battles. When not in use inside the Tridoron, Mr. Belt sits upon a station-pump like stand inside the Tridoron's Drive Pit which is located in the basement of the Kuruma Driver's License Center. After Shinnosuke gains the ability to transform into Drive Type Tridoron, Mr. Belt gains the ability to temporarily assume control of Drive's body and fights in his place. He also discovers that Banno is still alive, trapped in the tablet computer used by Heart, and is disappointed that his former colleague still wants to rule the world. After Banno and the Roidmudes are all defeated and the second Global Freeze is prevented, Mr. Belt projects a hologram of his original human appearance and bids farewell to his allies, sealing himself, the Tridoron, and all of the Kamen Rider arsenal away so it can never fall into the wrong hands in the future.
In Movie War Full Throttle, Mr. Belt was destroyed by Kamen Rider Lupin, whom took Drive's title as the "Kamen Rider". Although he was restored later because of Shinnosuke's desire to not giving up against Lupin, it was revealed that in Type Lupin! ~Lupin, the Last Challenge~, Go was partly responsible in his restoration, having visited the Drive Pit in his alter-ego Mach and deliver Krim's backup A.I. sometime during the movie.
In the film Kamen Rider Drive: Surprise Future, it is revealed that Roidmude 004, who has stolen Krim Steinbelt's appearance, has put a computer chip in the Drive Driver to corrupt Mr. Belt's AI. The presence of the AI corrupting chip is revealed by the appearance of Eiji Tomari, Shinnosuke's son from 20 years in the future, and its effects are compounded by the appearance of an apparently evil Krim Steinbelt ordering around Kamen Rider Dark Drive in the present time to cause the second Global Freeze. This leads Mr. Belt to plead with Shinnosuke to destroy him, particularly after Type Tridoron takes over his body and nearly kills both Shinnosuke and Go Shijima. However, this is all part of Roidmude 108's plans to cause the second Global Freeze, having posed as both Eiji and the Steinbelt as Kamen Rider Dark Drive. After he becomes the Paradox Roidmude, he discards the Drive Driver he had been using, but Shinnosuke and Kiriko restore it to working order and discover that the Tridoron Key that Shinnosuke used to become Super Deadheat Drive can be used to restore Mr. Belt to normal in the future Drive Driver, as Krim Steinbelt used a mind link technology to ensure he can be brought back to normal.
In Super Movie War Genesis, Shinnosuke meets a younger Mr. Belt when both the former and Takeru are brought 10 years into the past. Despite not knowing who Shinnosuke is, Mr. Belt allows to use the Drive Driver to become Kamen Rider Zero Drive through the Shift Speed (prototype) Shift Car. When Shinnosuke and Takeru return to the future, Mr. Belt and the Shift Brace stay in the past. Present day, Mr. Belt arrives in Tridoron to assist Shinnosuke, having remembered that in 10 years the latter would require his assistance. After the defeat of the Renaissance Gamma, Mr. Belt congratulates Shinnosuke on his upcoming marriage to Kiriko and seals himself and Tridoron once again.
Krim Steinbelt, as a human and as an AI voice, is portrayed by Chris Peppler (クリス・ペプラー Kurisu Pepurā), who also serves as series narrator.