First published in the manga magazine Opera in July 2006, Classmates has spawned multiple sequels and spinoffs: Sotsu Gyo Sei – Winter (Graduate – Winter), Sotsu Gyo Sei – Spring (Graduate – Spring), Sora and Hara, O.B., Blanc, Home, and Sajō Rihito no Chichi to Sono Buka.

On the day of his mock college entrance exam, Sajō suffers a panic attack, and reveals that his transfer to Touichikou was prompted by low test scores caused by his anxiety.

In their final year of high school, Sajō is accepted to study pharmacology at Kyoto University; when his mother is diagnosed with cancer, he introduces Kusakabe to her as his boyfriend.

In this spin-off series, Hara has an encounter with Aoto "Sora" Sorano at a bar in Ni-chōme, but rebuffs him upon discovering he is a student at Touichikou.

After Kusakabe spends a week in Kyoto visiting Sajō, they reaffirm their desire to marry at 20 and decide to start referring to each other by their first names.

Sora, having graduated high school, works as a fashion model; after a chance reunion with Hara, they begin to pursue a relationship.

Sajō, now in his final year of university and lacking a clear direction for his future, asks Kusakabe to take a break on their relationship.

[7] The series is noted as a departure from Nakamura's earlier and subsequent works, such as Double Mints [ja] and Kaori no Keishou, which typically focus on darker themes and erotic subject material.

[7][9] Nakamura has stated that she had created "aesthetically pleasing works" with "soft images" prior to the publication of Classmates, but did not have the opportunity to publish them.

[19] In North America, the digital distribution platform JManga released an English-language translation of the first volume of Classmates under the title Doukyusei in April 2012.

[24] In July 2018, Seven Seas Entertainment announced that it had acquired the North American license for Classmates, and began publishing the series in June 2019.

[25] Internationally, the series has been translated into French by Boy's Love IDP,[26] Spanish by Ediciones Tomodomo,[27] Italian by Magic Press,[28] and Polish by Waneko.

"[60] In his review for the Los Angeles Times, Charles Solomon called the plot "rather standard", but offered praise for film's watercolor-style animation.