Using the recollections of Keitaro from the other dormitory tenants to program the robot, Mecha-Keitaro had silicon skin, manipulators for arms and a turtle-like lower half. For combat, the robot possesses an energy shield and a retractible plasma cannon that emerges from its groin in a lewd display.
Able to speak, the robot's vocal synthesizer can be programmed via a laptop computer. The user enters what they want the robot to say on the laptop and the robot processes and "speaks" whatever was entered into the computer.
After Naru accidentally causes the computer to glitch while inputting a sentence for the robot to say, Mecha Keitaro goes on a rampage through Hinata; re-enacting Naru and Keitaro's first date in Hinata. However, due to too much activity the mecha's nuclear power core was on the verge of going critical, forcing the girl's to make the robot self-destruct to save the city.
- Naru and Keitaro's first date was on October the 21st. Mecha Keitaro's chronometer was glitched so that it thought that is was the day of the date and so re-enacted the day's events.
- The sentence Naru entered into the laptop that caused the robot to glitch was "I LOVE YOU NARUSEGAWA."