Hitoshi tells Forty about Twenty's early years. Before Twenty's current incarnation, she was a bundle of trouble. Hitoshi was a 3rd-year Junior High Student. Twenty flirted with Hitoshi, and made him buy her all sorts of clothes and make up. Secretly, Twenty's goal was world domination. She began to manipulate the Japanese military. Hitoshi sent in another A.I. program in to stop her. The other program used Twenty's insecurity about her weight against her, and managed to capture her. When Saati and Twenty must have routine maintenance work done, Forty is left alone to look after Hitoshi. Forty sees this as an opportunity to prove that she is an adult. She tries to take care of Hitoshi by doing the wash and cooking, but everything goes poorly. Forty changes herself into an adult body, modeled after Saatis, and Hitoshi finds himself attracted to her. Just as things get steamy Forty utters the secret password "man" and turns into a man. Hitoshi's little sister Yayoi comes to Japan in hopes of bringing Hitoshi back to America. Yayoi has a little A.I. program that she wears as a necklace. She is obsessed with other women's breasts, and is constantly fondling strangers.
She is surprised to meet Saati, and even more surprised when she learns that Saati is also A.I. Hitoshi refuses to go back to America, and calls Yayoi "flat chested" as he did when they were young. Yayoi is hurt and Hitoshi realizes that his brotherly teasing may have given her a complex. Later, the gang goes on a trip to the beach, and the girls all enter a beauty contest. Saati makes Yayoi's breasts look bigger, and Yayoi gets a boost of confidence. Yayoi wins the competition, and then learns that no one else could actually see her new, bigger breasts. She won the contest without altering her body. Hitoshi finds a new virus called "Spider", and isolates it on a disk. Yayoi sneaks over to Hitoshi's main frame computer and starts to use it. She puts in the spider disk, not realizing that it's a virus, and the Spider virus comes out of the computer in the form of a winged man. Twenty and Forty are infected by the virus. The virus escapes into the computer, and begins to do damage worldwide. Saati is the only program who hasn't been infected, and she wants to enter the computer lines to save Twenty and Forty.
Hitoshi tells Saati that she has become human, and that he loves her and tries to stop her from going into the phone lines. Saati says she doesn't care about being human; she just wants to live happily with the whole family. Saati enters the phone lines, and beats the virus, but dies along with Twenty and Forty. Hitoshi and Yayoi are on their way back to America...along with Saati, Forty and Twenty. It turns out that Hitoshi was able to recreate their program cores from the main frame. It looks like they will live happily ever after.