Mike Kamishiro, an independent computer programmer, bought a house after hearing about a report of a UFO seen in the area. However the house is not a compulsive purchase. His only recollection of the past is the memory of a girl. Bizarrely she could possibly be the twin sister of someone he rescues on the way to the house (Miina), a new girl in town. Later this same girl tells him that she is his sister. During this discussion, Karen, another new girl in town says that it she is also Mike's sister. Maybe they're relatives, maybe not.
Miina and Karen search for jobs, and they are going to find it... At the Mike's School! But in interviews, everything leads to all sorts of misunderstandings that lead to disaster ... Maybe they can scape, maybe not.
A quiet ride to the mall turns into a nightmare when the three Twins are lost and begins a drama to know where is each other. Maybe they have a storm in a glass of water, maybe not. (Moral: Always remember to carry a cellphone)
A former Miina's roommate appears and the Miina's past is revealed: an athlete who had to leave everything behind for an accident, the siblings will show her how valuable is to get up after falling. Maybe This is helpful, Maybe not.
While investigating an abandoned house across the road from Mike's house, Karen discovered Mike's sister. So before she reveals the news she decides to go out with Mike on a "date" to test some of her theories. However, Miina has also discovered the truth. Miina leaves the house, never to return.
Miina has left but has not got very far - Karen finds her at the school. Now Karen's task is to convince Miina to return home and see poor Mike. But Mike expresses his feelings towards Miina and Karen will make "a mistake".
Miina wants to be alone with Mike, Karen wants to be spoiled by Mike, but Mike wants to be... alone to catch up on work. In order to this, he asks for some help from Tsubaki and Shimazaki. But the student council, Miina, Karen and others arrive for a party. Morino makes a move and everyone (Including the cast of "Please Teacher!")is invited... with disastrous consequences.