In the first half of a two-part episode, after Akari suggests that between the stairs might be a gate to a parallel world, President Aria squeezes through and finds himself in world where the other characters are http://anidb.net/t6021 [of the opposite sex]. When he realizes what has happened, he begins crying and runs back to Aria Company to try to return home through the stairs. The male Alicia finds him there and tries tossing him in the air to cheer him up, then the female Woody takes him up in her air-cycle, but drops him. When President Aria comes to, he is back home.
In the second half, Arata tells Alicia and Akari a story, seen in a flashback, about his younger brother as a boy, when he pretended to be an http://anidb.net/t1278 [artificial human] who was the "protector of Aqua". When his brother teases him by pretending to have been replaced by an evil alien, Akatsuki runs away in fear, and is calmed by his mother bringing him his superhero cape and identifying him as artificial. In the present, when Akatsuki finds out what his brother has done, he goes into shock.