Nishioka is in a book store when he spots a salesman named Majime from Genbu Books doing a poor job. Meanwhile, the veteran dictionary editor Araki is searching for a successor as he prepares for retirement. Nishioka mentions his encounter with Majime. Araki heads to the sales department to meet this Majime.Upon meeting him, Araki sees Majime's potential and recruits him on the spot.

After Majime transfers to the dictionary editorial department, he learns of Araki and the supervisor Matsumoto-sensei's passion for dictionaries, and tell him of Daitokai, the dictionary they are working on. Majime is consumed with worry about living up to their expectations. His landlady, Take, tells him to simply depend on each other. That night, Majime encounters a beautiful girl on the balcony.

It's discovered that Majime has fallen for Take's granddaughter Kaguya. The editorial team decides to visit the restaurant where she is learning to become a chef. Majime is enamored with Kaguya as she answers Nishioka's questions. Majime admires Nishioka and his ability to engage people. Nishioka finds Majime's awkwardness entertaining. Nishioka hears a rumor about Daitokai being canceled.

To stop the rumored cancellation of Daitokai, the editorial team unites to implement Nishioka's plan. Nishioka has never felt more alive while successfully executing his plan. A few months later, Majime has a day off and Take pushes him to go out with Kaguya. The two of them make their way around Tokyo. Kaugya passionately talks of cooking. Majime is moved. That night, Majime begins to write a letter to express his feelings to Kaguya.

The director informs Nishioka the conditions for the Daitokai's continuation, which are the revision of another dictionary and Nishioka's transfer to the marketing department. Nishioka's shocked, but seeing the team's joy with the sample copies of Daitokai, he vows to do all he can before his transfer. Later, Majime works up the courage to hand Kaguya his letter.

The morning after handing her the love letter, Majime panics and runs when he sees Kaguya. That afternoon, Nishioka reveals his transfer to the shocked team. Majime worries over losing Nishioka. That night, spurred by Nishioka, Majime presses Kaguya for a reply. She's overwhelmed and retreats to her room. Majime thinks it's over, mildly depressed, but after rereading the letter she comes back and tells him she likes him too.

Spotting issues with a professor's manuscript, Nishoka and Majime propose amendments. Majime reaffirms that they need Nishioka. But Nishioka reassures Majime that he will always be there for him. A few days later, the professor is livid with the changes, and Nishioka goes to apologize. The professor is upset, but Nishioka manages to win him over. Nishioka and Majime go down their separate paths.

Kishibe is back and ready to work. She is enamored with Matsumoto and Majime's talk on words and dictionaries. The team is on the final phase, as a special paper is also being developed specially for Daitokai. The team unify in this home stretch. After roughly a year, the paper is finally finished. Daitokai is inching closer to being completed. However, a grave mistake is discovered.

The editorial team is dumbfounded by the discovery of an omitted word. Majime decides to recheck all 240,000 words. During all of this, Matsumoto is hospitalized. Majime frantically works to complete Daitokai. The team works tirelessly day and night under the same roof. Time passes, and the rechecking is finally completed. Nishioka comes to help celebrate. Daitokai is nearly completed, but...

Majime and Araki visit Matsumoto with an advanced copy of Daitokai. Matsumoto is pleased, but he tells them he has cancer. That spring, the team gets a call informing them of his death. Daitokai is completed, and they throw a party to celebrate. Araki reads a moving thank you letter from Matsumoto. Later, Majime reflects on Matsumoto's message as he walks with Kaguya, finding peace and solace.