Hiroto is a 29-year-old part-timer without a care in the world-no troubles, no lovers, no stable job. Twice a week, he visits the house of an elderly woman he met on a whim to share a meal with her. One winter, she suddenly dies, leaving the house to Hiroto. Three months later, Hiroto's sensitive cousin Natsumi comes to live with him while attending an art university.

Natsumi blunders through her self-introduction at art university and is convinced she blew her only chance to make new friends. Meanwhile, Hiroto hangs out with his old high school friend Hideki Noguchi, despite his concern over Natsumi's sullen mood. After some celebratory news, Hiroto's trip home is interrupted by a sudden phone call from Natsumi…

Yomogi Tachibana visits a fish pond where Hiroto works part-time. After watching her make busy phone calls while fishing, Hiroto ultimately does something to offend her. This bothers Hiroto until his friend Hideki brings high-quality beef on his way home from work. While the two of them enjoy a meal at Hiroto's house, Natsumi grumpily secludes herself in her room.

Returning from work, Hiroto runs into Natsumi at Asagaya Station. The latter has been skipping class due to her lack of friends and was wandering around town. Natsumi questions why Hiroto always seems so worry-free and his answer surprises her. Upon resuming class, she reunites with Akari Yokoyama, the girl who gave her water when she was drunk.

One day, Hiroto and Natsumi leave their tiny house to watch a movie. At the station, Hiroto encounters the woman he offended at the fish pond, Yomogi, whose values and pace of life vastly differ from his own. This makes her miss the train, and she becomes increasingly annoyed with him. Hiroto and Natsumi return home under a sudden rain to find a leak in their roof.

Hiroto is surprised when Yomogi is the one who arrives to fix their leaky roof. Natsumi notices the tension between them and laughs at seeing Hiroto lose his cool. As Yomogi works under the hot sun, Hideki arrives with a giant striped jack. The thought of sashimi puts Hiroto and Natsumi in high spirits, but…

After days of Nastumi demanding meat for dinner, Hiroto encourages her to find a part-time job. Natsumi fights back with a mysterious air of confidence-she's convinced that a rising manga artist's award will kickstart her career. Regardless, Akari gives her a job at a Chinese restaurant. Unfamiliar with the working lifestyle, she struggles through her first day.

Natsumi's friend Akari is coming to spend the night at the hiraya. As she cleans in preparation, Natsumi finds a DVD of a movie Hiroto appeared in and recalls his acting career. When Akari praises Natsumi's manga, Natsumi describes how Hiroto has encouraged her. She then thinks back on a summer day when she was in elementary school.

Unable to find any summer fun, Natsumi spends her first college summer in boredom. Feeling lonely while his wife stays with family, Hideki brings fireworks and some watermelon to party with Hiroto and Natsumi. While Hiroto makes a trip to the store, Hideki shows Natsumi a movie he filmed with Hiroto, which became a hit at their high school's culture festival...

It's time for Asagaya's annual star festival and the locals are making papier-mâché decorations to display. Hiroto's workplace gets help from the would-be genius Natsumi and the result is a truly creative design. As they deliver their decoration, they run into Yomogi who is annoyed by Hiroto's cheerfulness. The tension carries over to festival day, but…

After struggling to find inspiration for manga poses, Natsumi takes reference pictures of Hiroto, a former actor. She comments on this, and detects an uncomfortable expression on his face. Regretting her comment, she decides to apologize by buying him a birthday cake. Outside, she encounters Hideki, who informs her of Hiroto's failed acting career.

It's a mild sunny day and a chain of chance encounters leads Hiroto to believe something good is in store. Natsumi and Akari visit the fish pond but need lessons from Shibusawa, one of the regulars. Adult and child alike are having fun when Natsumi gets a fateful phone call and Hiroto receives a message from Hideki.

Aspiring manga artist Natsumi visits a publisher after her work is acknowledged. She tells Hiroto about this nerve-wracking experience as they prepare dinner. She retells having to wait an hour, meeting with vice editor-in-chief Nikaido, and everything he said. During her story, Hiroto recalls his first time visiting a talent agency with dreams of becoming an actor.

Hideki and his wife Saki visit the house with their baby. Hiroto excitedly prepares sandwiches to welcome them, and everyone enjoys their day off together. Natsumi, who initially found babies hard to deal with, becomes curious when faced with a real infant. Hiroto watches his friend's awkward but earnest efforts at childcare...

Natsumi believes that all manga artists are geeks, so she's kept her manga hobby a secret from everyone except Akari. Unfortunately, her secret is revealed to Nakajima, a classmate whom she dislikes. On top of that, she receives harsh criticism from her editor. Nothing's going well for Natsumi. Worried, Hiroto invites her to explore Asagaya. She aggressively declines.

One day, while walking a customer's dog, Hiroto bumps into Yomogi. This is followed by several other chance encounters that leave them both feeling awkward. When Yomogi's best friend Rei visits for dinner and asks about love interests, she denies having any. But when work leaves her frustrated, Hiroto appears again running at full speed...

Hiroto and Natsumi gather around their first hot pot meal of the winter. During the meal, they discuss how Hideki hasn't been around lately. Meanwhile, Hideki juggles work and parenting-a busy, busy life. Day after day, he's scolded by his wife and verbally attacked by Kiryuin, a colleague far more talented than Hideki himself. Hiroto tries sending him a message...

With his work and home life a mess, a depressed Hideki blocks Hiroto on social media. Hiroto is worried, and after recalling how Hideki was once there for him at a difficult moment, he runs to the furniture store where the latter works. Hideki is annoyed at first, but Hiroto's persistence eventually leads him to crack a smile…

One day, Hiroto and Natsumi are cleaning Hanae's altar. Hiroto remembers a time when Hanae called him a "friend." Meanwhile, Hideki's work life and parenting responsibilities are still eating away at him. Stressed and depressed, he stumbles home from work after being reprimanded by Kiryuin even more severely than usual. On the way, he makes a brief stop elsewhere...

Hiroto and Natsumi receive a box of sweet potatoes from their family in Yamagata and decide to hold a sweet potato stew party. They invite Hideki and Akari respectively. While Hiroto searches for a big enough hot pot, he finds a get-well card he had given to Hanae with a white hydrangea, her favorite flower.