Title: Fire Starter
Original air date: August 6, 2003

Summary:
Mamimi is obsessed with a hand-held video game called Fire Starter, which involves the player performing the role of an arsonist in order to please the Lord of Black Flames. The robot who had emerged from Naota's head is kept occupied doing chores at the Nandaba residence, while Haruko, despite being the maid, performs little to no work. Mamimi comes into contact with the robot while he is recovering the parts from his head that Haruko had damaged, and names him Canti, believing him to be the Lord of Black Flames of her game. Haruko tries to break into the Medical Meccanica plant in town, which is in the shape of a giant iron, but fails and is taken home by Naota. A series of fires meanwhile is erupting around the city, and Naota visits the site of one of these fires with two of his school friends, where he sees Mamimi down by the river and learns from his friends she is being bullied at her school. Naota realizes it is Mamimi who is starting the fires, and that she truly believes her game to be reality and the robot to be the Lord of Black Flames from her video game. He finds her performing a 'fire ritual' by the water bank. She explains she burnt down her old school house when she was younger because she 'hated the place', and had been saved from the flames by Naota's brother, the reason she loved him. A robot emerges from Naota's head then, and starts to battle Canti. Naota merges with Canti, and is able to transform into a large weapon to destroy the robot. At the end of the episodes Naota wonders what he can do for Mamimi, and promises to always be by her side.
http://en.wikipedia.org/wiki/List_of_FLCL_episodes