Yuusuke's father has moved abroad, and now Yuusuke has the house to himself. However, on his way to school, he stumbles upon (actually, falls on top of) a naked, sleeping girl in the forest, with a halo over her head. He runs away when she wakes up and declares that he's her husband, but he can't escape her - she's the new student in his class! Noelle follows Yuusuke home, and he discovers that her family of demons from the underworld have moved in - and redecorated.

Yuusuke is in love with his classmate Natsumi, who's on the diving team. She's a bit standoffish and doesn't take to him, especially after a couple of accidental incidents convince her that he's a pervert. He tells Natsumi that she's like an angel to him, but she rebuffs him. Noelle overhears this conversation and decides she's going to become an angel for Yuusuke. Meanwhile, Papa is trying to find a job and ends up promoting a wrestling champion named Delicious White. The family finds out that Deli-chan is actually working for a demon named Dispell, who has an unhealthy obsession with Noelle. Deli-chan kidnaps Noelle, and Yuusuke and the family have to rescue her.

Dispell, the villain, doesn't want Noelle to become an angel. To him, beauty lies in imperfection, and a haloed angel with no wings is beautiful and imperfect. He sends another demon, the cat-girl Miruru, to make sure Noelle doesn't succeed in becoming an angel, while his companion Silky sits passively by and echoes his lunatic ravings. Miruru obliges, though she'd much rather chase after Gabriel, Noelle's vampire older brother who has a terrible allergy to cats.

Yuusuke has developed a cold, and Noelle wants to make him feel better. Although she'd rather stay by him, he convinces her to go to school, where his friends Masaru and Saiki remark that he's lucky to have someone who thinks he's precious. Noelle doesn't know what the word "precious" means and tries to find out in class. Her teacher tells her that when you think someone is precious, it means you want them to find happiness. Miruru catches Noelle after school and tries to persuade her to go to a fancy restaurant with her, promising it will bring her true happiness. Noelle becomes extremely happy when she samples the dessert, Jasmine Jelly (it's pururun!), and decides to take it home to Yuusuke right away. Once she leaves the restaurant uproots itself and chases after her, trying to capture her to give her to Dispell. The restaurant is distracted by a giant cake and leaves Noelle alone - though it managed to smash her Jasmine Jelly before she could get it to Yuusuke.

Noelle's oldest sister, Sara, is invisible. At first she enjoyed being invisible, because people left her alone, but now she can't make herself visible again and feels alienated. While the rest of the family plays a mean game of beach volleyball, Sara meets Yuusuke at the beach, wrapped in bandages. She said he was the first person who's paid attention to her in a long time, and she could make herself visible in front of him. The two of them are interrupted when a UFO kidnaps Noelle. Yuusuke runs to save her, and Sara has to get help from the rest of the family - if she can get their attention, that is.

Because she wants to be Yuusuke's angel, Noelle starts her flying attempts, with the help of mechanical wings built by her sister Lucca. We see through flashback Natsumi's traumatizing memory of losing her older brother, Fuyuki. She's bitter about his death and is very annoyed with Noelle for endlessly talking about angels, but still Noelle follows her around and demands that Natsumi teach her how to fly. She goes to the diving team with Natsumi and attempts to dive off the high diving board the way Natsumi does. After all, Yuusuke said Natsumi was an angel, and every morning he watches her "fly" off the diving board.

A package arrives for Yuusuke --it's a squid! With a halo over her head! The family decides how they're going to cook her, until the squid announces they can't do that -- she's Noelle! After all, Noelle's family is not blood related, so what difference does it make if another Noelle moves in with them? She commences usurping Noelle's seat at the dinner table, Noelle's rice bowl, and Noelle's bedroom. To keep the family together Papa goes out and buys squid Noelle her own rice bowl. She's so touched that she confesses to Papa that she's not Noelle at all, much to Miruru's chagrin. Miruru asked her to disrupt the family and get rid of Noelle, presumably to drive her to Dispell.

In the first episode, Noelle and her family had to battle a giant rice-cooking Daruma, sent by Dispell, using a mecha built by Lucca. Now Lucca has updated the mecha and Noelle is the designated pilot. Meanwhile, Miruru convinces the Daruma's wife (with baby in tow) to wreak vengeance upon the family for taking her husband away. The Daruma's wife proceeds to attack Noelle, who refuses to fight back - she understands that it's painful to be separated from the one you love. Sara suggests they bring the Daruma back to life, so that there will be no reason for revenge anymore.

Granny doesn't want Noelle to marry an "impure human" so she goes off in a huff when the family starts discussing marriage plans (ignoring Yuusuke's objections). Miruru and Granny team up to try and get Yuusuke out of the picture (Miruru telling Granny that she loves Yuusuke and wants him for herself). So the newest robot has a ukulele that can turn people into frogs. Slowly each family member is turned into a cute little frog until Yuusuke is the only one left (Miruru betrayed Granny so even she is a frog) and has to figure out how to save everyone. He thinks you have to look into the ukulele's eyes but it's the strings that hold the magic.

Natsumi has a fight with Kai. Yuusuke and Noelle go to a festival and Noelle receives a little creature called Bunbun ("Boonboon"), who supposedly will turn into a angel with 7 color wings if it's taken care of properly. Yuusuke has a bad feeling about the little guy though since it refuses to let Noelle sleep in Yuusuke's room and she even left for school without him the next morning. When it goes cray and eats all the food at the table when Noelle runs off to get some napkins, Yuusuke is convinces Bunbun is bas news, but Noelle refuses to believe him. When Yuusuke yells at her to get rid of it, Noelle seems like she's about to say "I hate you!" but instead says "I still love you!" so Miruru pops out, disappointed that her plan to break up Yuusuke and Noelle didn't work. Bunbun then goes berserk and drills holes into the walls of the house, making the whole thing look like Swiss cheese. Bunbun goes after Noelle and Yuusuke saves her. Lucca then fixes the old Bunbun into a proper, non-evil, creature and Noelle celebrates.

A comet is coming and it's got Mikael worried for Noelle. Yuusuke and Natsumi are chosen to be the class representatives on the committee for the school's Durian festival to celebrate the comet (that looks like a durian fruit). Yuusuke has a chat with Kai, learning about the relationship between Kai, Natsumi, and Natsumi's dead brother Fuyuki. Kai was always in love with Natsumi but she only ever saw him as Fuyuki's friend, then when Fuyuki died she started to hang around Kai more (likely using him as a replacement for Fuyuki). Mikael speaks to Yuusuke, telling him to not let Noelle out of his sight and Yuusuke goes to find her. She's with Lucca at the school's clock tower, they were going to use the comets power to help Noelle fly, but the clock started to wing backwards, catching the hose attached to Noelle's mechanical wings and lifting her into the air. Yuusuke arrives just then and helps get her down before running up the clock tower to see what was happening. When he gets there, he finds Natsumi, but she's become a child again!

Child Natsumi is staying with Yuusuke and the others at his house. He tells the school he, Noelle, and Natsumi all got sick and his friends take over the committee positions, but they're not buying the sudden sickness and pay Yuusuke a visit. So Yuusuke comes clean and tells them about Natsumi and his friends say they'll help him cover it up as long as he can find the cure. Yuusuke tries to take Natsumi back to the clock tower to find clues but she refuses and runs off. Later, Noelle remembers seeing Natsumi at a grave and that's where they find her. Yuusuke tries to explain to Natsumi that she has to let her brother go, he's never coming back, and she'll stay a child forever if she can't accept that, but all this does is make Natsumi mad at and scared of Yuusuke. She retreats into the (weird) hole in Yuusuke's room, covering it with cardboard and refusing to come out, throwing stuff at Yuusuke when he tries to go in. Meanwhile, Noelle is practicing on the room of the school with the heavy mechanical wings for the day the comet comes. Sara and Gabriel seem a little concerned that Yuusuke is spending so much time and energy on Natsumi, and Lucca tries to point out to Noelle that Yuusuke would probably rather become Natsumi's angel than for Noelle to become him, but Noelle doesn't seem to understand what Lucca is trying to say. On the day of the festival, Yuusuke is fed up with Natsumi hiding and goes to get her out, but she's ready and runs up to the roof. Yuusuke has a heart to heart with her, he explained how at first he thought they had the same kind of sadness over losing people they love, but he'd realized that they were different pains after all (since he is still able to actually see and speak to his parents since they're not dead, unlike Natsumi's brother). Yuusuke and Natsumi both decide to make a wish on the Durian comet to wish for Natusmi to be able to see Fuyuki again.

At the festival, Granny is running a fortune telling stand. She sees Mikael walking past and invites him in. We discover that Granny knows who Mikael is (or at least knows he's been encouraging Noelle's endeavor to become an angel) and tells him to leave Noelle alone. Yuusuke and child-Natsumi are on their way to the festival to make their wish. Miruru is confronted by Dispel, who has come to capture Noelle himself. He tries to kill Miruru but Gabriel steps in and saves her. He realizes that he's not itchy and theorizes that since he drank Miruru's blood (a few episodes ago) he's immune to his cat allergy now. The comet is over head and Noelle is preparing to run like her and Lucca had been practicing, when Dispel drops in and throws Lucca through the clock tower before chasing after Noelle who tried to run away. Yuusuke and Natsumi had been on their way to the top of the clock tower to make their wish when Lucca came crashing through. Yuusuke's friends and their teacher see Dispel going after Noelle and throw their durian's at him to try and slow him down. Noelle and Dispel end up at the top of the clock tower. Yuusuke tries to help but gets blown off the building. He's trying to hold on to both the building and Natsumi while Disple tries to kick him off. Yuusuke and Natumi fall and Noelle jumps after them. There's a flash of light, Noelle's halo flashing and expanding, and her mechanical wings take flight, enabling her to save Yuusuke and Natusmi, all three of them safely landing on the ground. Disple, believing that he failed in preventing Noelle from becoming an angel, leaves. Natsumi, who had a vision of her brother telling her to let him go and move on, has turned back into her normal self to Yuusuke's relief. Back at the lair, Dispel is upset and Silky, his supposed slave, tells him Noelle isn't an angel yet and says she's bored now. She was apparently in charge the whole time, Dispel just being a doll. Back at the school, Mikael is trying to figure out what