The episode starts with three members of different factions listening to a special newscast about an alien message, the first part of which has been translated to mean "coming to play". One of the members is then called to battle aboard an enemy ship. She successfully infiltrates the ship and disarms the Captain. The situation is disrupted by a UFO passing too close to both ships. When the same member comes to, the enemy captain detonates the ship. Later, during a memorial service for one of his ancestors, Kio Kakuzu finds a cat-like alien sitting at the buffet table. The alien introduces herself as Elis, and the two have a short conversation before Kio accidentally drinks beer and passes out. The next morning, Kio wakes up with a hangover and finds Elis sleeping half naked next to him in bed. Kio's startled cry wakes her up, and she heals his hangover with a handheld device. Manami Kinjō and Maki Itokazu then visit Kio, and upon seeing Elis half naked and with cat ears and a tail, they misinterpret the situation, thinking that Kio brought a girl home and forced her to cosplay all night. After discovering that Elis is an alien, they both abruptly leave without saying why. Kio goes on a walk to gather his thoughts and runs into Aoi Futaba, who asks Kio on a date. Aoi is interupted by a man in a car who she names as her Uncle. He offers her a ride home. It is later revealed that Manami is in recruiting to become part of the CIA, Aoi is a Momiji for the Immigration Bureau of Japan, and Itokazu is the leader of an organization of SF fans called "Beautiful Contact", and they are all given orders to eliminate Elis.

Manami and Aoi watch Kio and Elis, both waiting for a good time to make their move. As they are waiting, however, Itokazu and "Beautiful Contact" jump Kio and Elis, and are about to kill both of them when Aoi disobeys orders to wait and saves Kio. She then moves to kill Elis, but Kio begs the Momiji (not knowing it is Aoi) to spare her. She obliges, but as soon as she leaves, Manami appears with CIA back-up, knocks Kio out and captures Elis, but not before Kio sees Manami's watch and knows it is her. Later, Kio confronts Manami and begs her to help him find Elis. Manami contacts Aoi for extra help, and, receiving help from his uncle, Kio blackmails Itokazu and Beautiful Contact into helping as well. Together, they succeed in breaking into the military compound where Elis has been given to the DIA, only to find that she has already broken herself out. The episode ends with the rest of the Catian fleet appearing over the city, announcing their existence and their intent to negotiate a treaty with the Japanese government, as a result of Elis submitting a report about grilled beef.

Elis, along with other ranking officers, negotiate with the Japanese government wearing stereotypical school swimsuits, due to misinformation on Elis' part. Upon returning to Kio's house, Manami and Aoi visit, again misinterpreting the five Catian women dressed in revealing clothing standing in Kio's living room. They state their intention to leave, since the events of the previous episode marked them as traitors to their respective factions. Elis tells them that since Kio's house is now a Catian embassy, everyone inside is protected by Catian laws, and the two girls are invited to live there as well. Later, while the robotic servants are on guard duty and Manami and Aoi are bathing together, one of the robots is abducted by members of a yet unknown faction. Manami and Aoi spring into action, rescuing the robot, although the intruders escaped by use of a stun grenade. The next morning, Manami, Aoi, and Kio are hired by Elis as official embassy employees. Manami discovers Aoi's feelings for Kio, and offers to help her out, though Manami's reactions throughout the episode lead Aoi to suspect that she may have feelings for him as well.

The episode opens on a concert hall filled with members of Underside of Kitten Paw, a fanatic group obsessed with cats. Their leader, Antonia Morfenoss, shows pictures of Elis and declares her to be their new idol of worship. When Kio wakes up, he walks in on Elis dancing and being abnormally energetic due to having smelled silver vine spirits, an Asian plant reported to be stronger than catnip. Dr. Dyureru appears and explains that Elis will soon be going into heat, causing her to have heightened senses, and congratulates Elis on having a mating partner on her first heat, much to Manami's outrage and Kio's embarrasment. She also assigns Elis a mission to go into Tokyo and "observe the human economy, technology, and culture", which, according to Elis, means to bring back a bunch of toys and games as souvenirs. On the train back, members of Underside of Kitten Paw separate Elis and Kio from Manami and Aoi, putting them to sleep and showing the sleeping Elis live to the screaming fans of Underside of Kitten Paw.

Kio and Elis wake up inside a yacht owned by Antonia. They are soon greeted by one of Antonia's maids, who offer them trays of gourmet food. After eating, they decide to escape, but to their dismay Elis' power suit has been limited due to Elis being in heat. They are taken to a play room with Antonia who is dressed like a giant AssistDroid. Kio notes that all of the video games have been fixed to only accommodate one player, due to the maids not having the heart either to beat their master in a game nor lose intentionally. Meanwhile, Aoi and Manami visit a weapons store and stock up. While there, they ask for a motor boat and are told the only one was sold to Director Kawasaki for his upcoming film. The girls infiltrate the set and rig the boat with real weapons, but they are caught by Kawasaki, who contracts them into his film. After being forced into Playboy-like costumes, Aoi and Manami steal the boat and break into the yacht to find that Kio and Elis have switched clothes, enabling Kio to use the power suit's strength-enhancing capabilities. They are stopped by Antonia and one of her maids, but Kio convinces Antonia to let them go. Antonia offers them escape in the emergency sea plane. Aoi sabotages the ship's engines, but is caught by an agent of Dogisia, who is destroying the ship in the hopes that it will take Elis with it. Aoi is trapped by a pile of steel girders and then knocked unconscious by a missile explosion, to be saved by Kio still in Elis' suit. As Kio runs to catch the plane, Aoi regains consciousness and, thinking it is a dream, confesses to Kio.

Kio takes Elis to a film shoot directed by one of his classmates, who is trying to film a sci-fi movie and would like Elis' help in getting footage of aliens without special effects. They decide that Elis looks too human, and instead ask her if they could use her ship or her robots. The footage of the ship looks like it is being held by strings due to its design, and the robots look more like chibi dolls. They decide to go for a romance film. Upon hearing this, Elis' hormones go berserk and she assaults Kio, something she has done several times earlier anytime something one has said sounds similar to romance or sex. Meanwhile, Aoi wants to practice cooking to impress Kio, but due to her frequent failures she wastes a lot of food. At the same time, Manami wants to practice shooting, but she can't do it in Kio's backyard. Chaika takes them to a virtual room on board the mothership, where they can fulfill their respective desires without it bothering anyone. She also makes it a point that the Catia without mates use it to satisfy their sexual desires during heat and offered if they would like to try it out as well, much to the girls' embarrassment. Aoi asks for a Kio to be her taste-tester. Manami asks for a shooting gallery with a wide assortment of weaponry, and for an M134 Minigun in particular, which turns out to be too heavy for her to lift. She asks for a Kio to help her lift it, who tells her in a very Kio-like manner that he can't lift it. Manami asks virtual-Kio what he thinks of various people, eventually ending up on herself. He confesses that he once had feelings for her, but when he heard she was hanging out with Jack (unaware this was her female CIA handler), he thought she was already dating someone and she ended up being just a friend. Back at home, Aoi gives the real Kio a taste of a recipe she "perfected" with virtual-Kio, only to find out that virtual-Kio had lied to make Aoi feel good about her cooking. Chaika points out that virtual-Kio and t

The summer is over, and Kio, Manami and Aoi all return to school. To their surprise, they find that Elis and Antonia have enrolled in the same class as them, as well as Antonia's maids. After school, Elis and Antonia garner excessive amounts of attention to the point that Antonia's maids scare off other students with uzis. Kio's club-mates ask him if he is going to the film camp, and asks Elis if she would like to go on the trip as well. As a result, Elis, Antonia, Aoi, Manami, and Antonia's maids all become members of the film club with the intention of going to the camp. Meanwhile, a group of Dogisian AssistDroids are robbing surrounding areas of electronic equipment, due to their inability to self-repair. The Dogisian ambassadors reveal a specially made AssistDroid that closely resembles a Catian AssistDroid. Once at the camp, Antonia offers Elis a number of high-end swim suits for her to wear. When the other girls inquire about all of the ones that Elis refuses, Antonia allows them to wear the ones Elis doesn't like. Later, when they are all showing off their expensive swim suits, the girls realize to their dismay that they have all had holes cut in the rear to accommodate Elis' tail, due to one of the girls mistakenly wearing her bottom piece backwards. At dinner, Kio asks if he can talk to Aoi about something in private, but ends up asking if she can teach him to fight. Once alone, Aoi realizes that she is out of her league in the running for Kio. Elis appears, and Aoi takes out her frustration on her. Suddenly a young girl named Ichika appears, and at the same time, the camp gets attacked by the Dogisian AssistDroids. They are easily defeated with the help of some Accel-Form cards that give Aoi inhanced speed and strength, and later when the specially made Dogisian AssistDroid appears to help them in their fight.

Aoi and Manami decide to have a showdown in a nearby forest to settle their differences, but their match is cut short when they must join forces to defeat some assassins sent to take both out, the winner was therefore Manami. In the end Aoi had to pronounce Kio Kio Kun but doesn't take notice at all Manami then acted violantly.

Kio and friends are visited by Chaika, the first Assist-a-roid created by the Catians, who came to fulfill the last wish of her creators, who died while trying to reach Earth 1000 years ago.

It's Christmas and the Catians decide to prepare a special present to mankind, while Kuune, the captain of the Catian mothership pays a visit to Kio's house. However, the festivities are interrupted when the Dogisians launch an attack on them.

With the Catian ship en route of collision with Earth and Kuune out of commission, Kio is appointed the new captain of the Catian forces, and he sets with the girls to an abandoned launch base in Russia as part of their plan to aid their friends in space.

While struggling to save the Catian ship, Manami and Aoi finally manage to convey their feelings to Kio while Elis states that according to Catians' law, all three can be his lovers. After solving their situation in space, the Catians finally unveil their Christmas present to mankind; a fully functional space elevator.