Nasa Yuzaki was preparing for his high school entrance exams one snowy night when he spots a beautiful girl on the other side of the road. Feeling somewhat drawn to her, he walks towards the girl and is severely injured after getting run over by a truck. Despite hanging on for dear life, Nasa still walks over to the girl and knowing this may indeed be his last chance, confesses his feelings for her. She replies, “I’ll go out with you if you marry me.” Nasa immediately agrees but then loses consciousness. A few years later, he keeps busy at his part-time job, believing they’ll be reunited again someday. One day, someone randomly shows up at his doorstep. It happens to be the girl he shared that fateful encounter with.

Nasa and Tsukasa have submitted their marriage registration. As the newlywed couple approaches their first night together, they realize Nasa’s apartment doesn’t have enough necessities for two people, leading to Tsukasa suggesting she spend the night at a hotel. But Nasa stops her, and proposes they go shopping instead. After returning home, Tsukasa sleeps relaxedly while Nasa is tense with excitement from seeing a new side of his wife.

Nasa and Tsukasa’s newlywed life has finally begun. The two of them head to a bathhouse run by a girl who went to middle-school with Nasa, Arisugawa Kaname. Kaname is shocked to see Nasa with a girl, and is curious about what happened after learning about the marriage. Meanwhile, Tsukasa heads into the bath and encounters Kaname’s sister Aya. When she asks Tsukasa about her connection to Nasa, Tsukasa replies that they are family.

As Tsukasa waits for Nasa to return home, a young girl named Chitose, who calls her “Nee-sama” confronts her. Chitose asks for Tsukasa to come home with her, and after being ignored, encounters Nasa. He tries to cheer her up, but after learning that Nasa is the one married to Tsukasa, Chitose’s attitude suddenly changes. As Nasa tries to explain, Chitose shoves him into a black car that then drives away.

During the ruckus as the Kaginoji house, Nasa and Tsukasa pledge their love to each other at a church. After Nasa reports to Kaname that he has finally proposed, she points that he still doesn’t have a ring. Although he doesn’t take much notice at first, Nasa gradually becomes more self-consciousness about the role of a ring in newlywed life.

Nasa realizes he’s been so enthralled with newlywed life he forgot to tell his parents he’s gotten married. He tries to wrap it up with a simple phone call, but Tsukasa decides she wants to meet his parents. While Nasa is anxious about a potentially embarrassing meeting, the two of them head to visit Nasa’s parents in Nara.

Nasa and Tsukasa take an overnight bus to visit his parents in Nara. They attempt to enjoy the trip like a honeymoon, when Chitose shows up at a service area, asking to know why Tsukasa married Nasa, who happens to overhear the conversation and begins to wonder the same thing. As the couple attempt to enjoy seeing the sights in Kyoto, Chitose appears again. She attempts to test Nasa to see if he’s worthy to be married to Tsukasa, and he explains why he decided to marry her.

Nasa and Tsukasa arrive in Nara and head to the Yuzaki family’s house. Despite demanding to meet Tsukasa, Nasa’s parents, Enishi and Kanoka, are both clearly nervous. And not long after introductions, Enishi ends up making a deal with Tsukasa.

After returning from Nara, Tsukasa and Nasa find themselves without a home thanks to a freak lightning strike. Nasa's prepper habits keep the damage to a minimum, but they still find themselves temporarily homeless, until someone offers to let them stay in a spare room. And so, the newlyweds begin their stay at the Arisugawa house.

Nasa and Tsukasa are now enjoying newlywed life as guests of the Arisugawa family. Things proceed normally until they receive a call from Nasa's previous landlord, offering them an apartment at a newly constructed building. The two of them go to check out a showroom of their potential new home, arriving at a high-rise apartment building.

Nasa suggests takoyaki party to the Arisugawa sisters so that everyone can get to know each other better. Meanwhile, Chitose tracks Tsukasa down to the bathhouse. The game-loving Aya finds herself getting along with the two of them, and before long competitive sparks start flying!

Nasa comes down with a fever while at work. Despite his claims of being fine, Tsukasa takes him to the hospital and starts to nurse him back to health. After recovering, the two of them head to a summer festival. When Nasa begins to wonder about how many people out there worry about him, Tsukasa has something to say.

When Nasa is suddenly called in for some work, Tsukasa spends her first night alone since their marriage began. As the loneliness pulls at her, she takes the smartphone that Nasa got her as a gift in hand and continues to wait. Messaging allows the two of them to stay connected, even while separated.

Never one to miss a chance to pry into the Yuzakis married life, Kaname proposes a provocative question: cosplay, yes or no?

Does a marriage need a wedding? The Yuzakis grapple with that question, as Nasa learns just how daunting the ceremony can actually be.

Old friends resurface in Nasa's life, as he introduces Tsukasa to his old teacher Yanagi Naoko.

Tsukasa and Nasa head to a big-name theme park, where they have a run-in with Nasa's old teacher, who might be in the middle of her own romantic encounter.

Nasa's knowledge is a big help to the people around him, but even he's not sure about the list Kaname finds on the internet that describes the symbolism behind different kisses.

Thanks to Kaname, the Yuzakis find themselves on a honeymoon trip to Kusatsu, home to some of Japan's most famous hot springs.

The Kusatsu trip continues, but will Nasa work up the courage to ask Tsukasa to join him in the hot springs?

Scorching summer heat motivates the Yuzakis to purchase a new air conditioner, which ends up resulting in some new encounters.

Nasa is forced to consider how verbally intimate he is with Tsukasa, before Kaname encourages the two of them to get physically intimate in the bathhouse after-hours.

After Tsukasa grapples with her technological anxieties, the Yuzakis are greeted by two different visitors.

The Yuzakis are joined by friends and family for their camping trip, but can Nasa overcome his inexperience in dealing with the outdoors?

As the sun sets on the group camping trip, Tokiko and Kaname have a special surprise in store for the Yuzakis.

Nasa and Tsukasa are back home just in time to find out that they'll be moving into a new apartment soon, and Tokiko has something important to tell Nasa.

In an attempt to help pave the way for Yanagi-sensei's wedding, Nasa ends up teaching a programming class at a girl's high school.

Nasa's new students keep making unexpected appearances in his life, and Aya lets her imagination run away with something she saw on TV.

After a texting mix-up, Nasa is recruited to help one of his students confess her feelings to the guy she likes.

Gekko Kaguya is Nasa's brightest, and most mysterious new student. What is her connection to Tsukasa, and what might it mean for the future?