Canti is a robot from Medical Mechanica which appears from Naota's head and is taken in by Haruko as an assistant.
Canti is a medical robot with what looks like a television set for a head. He was manufactured by Medical Mechanica, but taken over by Atomsk as a way to escape Medical Mechanica. After having his head broken by Haruko he is recruited by her as an assistant, however he proves to be no good for much other than washing dishes and fetching drinks for the family. It is later revealed that Atomsk can manifest through him, with Naota being the catalyst. Atomsk's symbol appears on Canti's screen when he absorbs Naota; the symbol is a corruption of the kanji characters for "adult". This symbol also appears on him when Naota "swings the bat" in Full Swing and when Canti is absorbed by the terminal core in FLCLimax.
The emotions of Canti are very human-like, despite his looks. He is embarrassed about his broken head (where Haruko hit him) and is looking for the pieces to glue back together in episode two. He wears the box on the back of his head for the same reason- shame. He is also extremely polite, extending a helping hand to Lieutenant Kitsurubami even after she attempted to destroy him.
Canti also dons a halo and fake wings (which Haruko was wearing in early episode two). Mamimi is convinced that Canti is an angel. She calls him Lord Canti after "The God of Black Flames" in a video game she plays. The rest of the cast call him by this title throughout the rest of the series. Apparently, he can also eat curry with his "mouth," but it is never really explained how.