Episode 1
Keitaro 15 years ago with his girlfriend talking about how two lovers can go to Todai and live happily ever after, so they make a promise to go into Todai together. Soon after, his girlfriend has to leave and says "Kei-kun! bye bye!" from the window of her truck, which is the last time Keitaro sees her. Then we see Keitaro makes it into Todai, everybody's cheering for him and all the girls want him, he meets his girl, they get married, and live happily ever after.
Then he wakes up from his wonderful dream. Now we see the horrible truth: he's a 20 year old virgin, who lives with his parents, can't get into Todai. He's desperate and likes to collect sticky pictures of himself. He now has to go live with his grandma (with whom he had a very scary encounter in his dream...) because his parents can't feed him. Hina, his grandma, is retiring and needs to see him. Only the first episode and we already meet the "old men" who keep talkin about dreams and actually pick on Keitaro at one point in this episode.
Keitaro then goes to the preperation center to check the results for the last Toudai exam... and he's 27th place!!!... from the bottom (congratulations, it's the 3rd time you fail!). Meanwhile he meets Naru in her nerd form, and, after she falls in fear of getting his bad grades, she hits him because he saw her undies, making him bouce up and down, left and right all along the hall way.
Later, he sits down a while and tries to draw the girl with whom he made the promise 15 years ago. He can't remember her face or even her name. He sees a girl, Shinobu, sitting, and obviously sad, on a bench. Keitaro draws her smiling. After three old men steal his sketch book and toss it around, it is thrown and lands near her. To Keitaro's misfortune, it opens up to the page where he just drew her. Keitaro, embarassed, runs the hell away crying his usual cry: "tehehe!!!". After running a couple miles, he ends up at Hinatasou, his grandma's Inn. He looks around inside but can't find anybody. To his surprise, he finds the onsen (outdoor hot springs)! During his nice hot bath, Naru (this time in her normal form) steps in thinking, without her glasses, that it's Kitsune taking a bath along with her. You can no doubt imagine how Keitaro's feeling while seeing a beautiful woman naked (well actually she has a really small towel...). Naru runs in terror yelling out "PERVERT! PERVERT!" while holding Keitaro's... ahum... She finally lets go... but he lands in a basket full of Kitsune's undies. Result: "Come back here you undie thief!". He runs away from Naru and Kitsune, only to arrive in front of Kaolla's "Hinata Defense Force" (a line of miniature, but powerful tanks). After being blown out of the Inn by the tanks, he finally finds Haruka, his aunt.
Keitaro then figures out Hinatasou is an all girl's dorm. Haruka explains that Keitaro is the new Kanrinrin (manager) of Hinatasou. To help the girls accept him Haruka tells them that he's a Todai student. Naru is still outraged. Kitsune (this is one of her bad habits) plays around with Keitaro, and tricks him into doing her homework for a month. Keitaro later sees that nerd from the prep school (what the hell is she doin here?). Oh my god it's Naru! Oh no! she knows I'm not a Todai student! After Naru trips, Keitaro and her have a "romantic moment"... and to his luck she conceals the secret when Kitsune and Kaolla come to see what's going on. To solve all perverted problems, Keitaro get's his own "men's bath" (haha a barrel with warm water on the porch^_^). For a finishing touch to the episodes, Keitaro peeks at Naru while she's taking a bath and gets knocked out of this world.

Episode 2
This episode starts at Shinobu's house where she's sad. After the encounter with Keitaro in episode 1, we see that the three old men (who were picking on Keitaro) tell her he's going to Hinatasou. She then goes to school where she's pretty much rejected. She walks around and finds herself at Hinatasou, where she meets Kitsune, Naru, and Kaolla. Kaolla "knows every student in the school", and treats shinobu as her friend (she's desperate for someone to play with). Later, Kitsune, Keitaro, and Naru want to go eat at the Hinata restaurant (they can't stand Kaolla's extremely spicy food), but it's closed. Everybody's talking about Shinobu, and Haruka explains that her parents are divorced and don't have enough money to keep her. In his dream, Keitaro sees Shinobu leaving in a truck and saying "bye bye!"... An other comparison with his "15 years ago's promise girl". When Shinobu goes back to Hinatasou, she's greeted with a "farewell party", unfortunatly with unedible party food. We soon discover she's a great cook, she makes a remarkable meal out of Naru and Kitsune's meal. Later Shinobu's parents come looking for her (but naturally nobody wants her to leave). Keitaro agrees Shinobu can stay. Keitaro and Shinobu go on the roof. She talks to him about how sad her life is, etc. but he's just pretending to pay attention while he's eating her cookies ^_^. She basically says she's not smart enough to get into Todai and she has no friends... Still, Keitaro encourages her by telling her "If I can do it, so can you". They're interrupted when her parents finally find her on the roof. They tell her to come, she says she doesn't want to leave, she says she wants to stay in Hinatasou. Naturally, Keitaro lets her stay if she'll cook everyday.

Episode 3
This episode introduces Aoyama Motoko. The first three minutes look like one of those very old samurai movies, with a Kenshin theme. As you've probably guessed, these three minutes show Motoko in her training. The three meet Motoko followed by her fanclub on a bridge. Haitani and Shirai start flirting with the girls. Result: Motoko beats them up (Keitaro included) with an umbrella. Haitani and Shirai got the hell out of there, but Keitaro stays to get another attack from Motoko.
You'd think he'd leave this mysterious kendo woman alone after having the luck of surviving two attacks, well no. He sees her at Hinatasou in a towel taking clothes out of the washing machine (Motoko doesn't know he's the Kanrinrin yet). Naturally, her first impression of Keitaro is: stalker. I'm not sure I even have to mention he's the victim yet another attack.
The next scene takes place at the dinner table, where Motoko explains her outrage: "Having a young man living under the same roof is nonsense!". This poses a problem because first of all the other girls, except for Naru kind of, don't mind his stay at all, and second of all he's already kanrinrin. When Motoko leaves, Naru explains Motoko's background: she's an amazing swordswoman, she's already a master at fifteen, she used to train in a dojo in the mountains of Kyoto that was built to fight evil demons eons ago. Nobody really knows whether to believe this story or not, but it still scared Keitaro.
Afraid for his life, Keitaro decides to apologize, so he goes on top of the roof where Motoko's cutting the falling leaves. He gets hit by two attacks.
When Motoko's walking down the street, she fears that the reason for her not feeling well is because Keitaro is her first love (she actually just has a cold...). She fears this because, as we see in her flashback, her big sister, also a kendo master, left her and the way of the sword for a man, a painful memory.
Keitaro discovers a hole connecting his and Naru's rooms (Naru on top). He sticks his head through the hole and sees Naru, who thinks he's peeping. Motoko thinks he made the hole, and gives him another slash with the sword. Motoko doesn't feel satisfied, so she wants revenge on Keitaro for playing with her emotions. She gives him a sword and they fight for the position of Kanrinrin of Hinatasou. Keitaro's head pops up and sees Naru getting dressed. The result Keitaro gets a good punch. After being chased all around the Inn, he gets cornered on top of the roof. Right when Motoko's about to give Keitaro her finshing move, she faints (she has a cold) and starts rolling down and off the roof. The bold Keitaro dives and catches her. He saves her life, wins the fight, he's happy for once. But what's this? The girls find his memo book, which he lost after the fall, where they see he's not a Todai student. It was too good to last.
In the end we see Haitani, Shirai, and Keitaro (the four-eyed threesome) at the prep school where they see literally 0% chance of passing on their practice Todai test.