The series follows Kaoru Nishimi, an introverted high school student who discovers jazz music through his friendship with his delinquent classmate Sentarō Kawabuchi.

Critics explored Kids on the Slope's depiction of Catholicism in Japan, its themes of male friendship and subtextual homoeroticism, and its relation to Watanabe's broader canon of works in their analysis of the series.

Kaoru Nishimi is an intelligent, introverted first-year high school student from a wealthy family who moves to different cities frequently as a result of his father's career.

[32] Maruyama stated that Watanabe initially resisted the prospect of creating an adaptation and expressed concerns over a lack of creative freedom, but agreed after learning that the series was about jazz (music frequently forms a core element of Watanabe's works),[4][30] and after Kids on the Slope network Fuji TV agreed to greenlight his subsequent anime series Terror in Resonance.

[33][34] After reading the original Kids on the Slope manga, Watanabe noted that while jazz music forms the basis of the story, he was interested in its approach to plot and characterization, particularly "the kind of way that it portrays emotional distance.

[30][31] While Kanno has stated that she is not a fan of jazz music,[35] she sought to be involved in Watanabe's next project after their previous collaborations on Macross Plus and Cowboy Bebop.

[4][32] Watanabe and Kanno found jazz artists to perform the series' soundtrack and motion capture by searching videos on YouTube.

"[4] Pianist Takashi Matsunaga and drummer Shun Ishiwaka were cast to record the music and motion capture for Kaoru and Sentarō, respectively.

[13] Kōji Yamamoto, the producer of Fuji TV's Noitamina programming block, confirmed that same month that the series would air on the network beginning in April.

[40][41] An English language dubbed version of the series was also produced by Sentai Filmworks; episodes aired on Anime Network and Hulu one month after streaming on Crunchyroll.

[47] Kids on the Slope publisher Shogakukan confirmed the adaptation the following day, along with an announcement of the film's cast and primary production staff.

[48] The film is directed by Takahiro Miki with a screenplay by Izumi Takahashi [ja], and stars Yuri Chinen as Kaoru, Taishi Nakagawa as Sentarō, and Nana Komatsu as Ritsuko.

In 2009, EMI Music Japan published Kids on the Slope Original Soundtrack, a compilation album collecting songs referenced in the manga series.

[14] Jazz figured heavily in Sasebo's music scene beginning in the 1920s and 1930s; the city houses a major naval base for the Japan Maritime Self-Defense Force (then the Imperial Japanese Navy), which attracted nightclubs and cabarets to the area.

Drazen further identifies Kids on the Slope as an example of a work that juxtaposes Catholicism and Western popular music, comparing it to media such as "Dominique" by The Singing Nun and the Sister Act series of films.

[34][38][58][59] Jacob Parker-Dalton of Otaquest cites the series' homoerotic subtext as an example of the influence of the boys' love genre (male-male romance) on the josei demographic, noting how Sentarō and Kaoru conform to typical seme and uke ("top" and "bottom") character archetypes.

"[34] Ashby notes how the series' theme of male friendship is one that recurs in Watanabe's works, which depict "unlikely pairs of men (or boys) who are either thrown together by circumstance or are drawn together by their mutual histories.

[68] Theron Martin reviewed the series positively for Anime News Network, noting that while Kids on the Slope is "more pedestrian" than Watanabe and Kanno's previous collaborations, he offered praise for its character development, music, and visual style.

"[69] Kirk Hamilton of Kotaku wrote that while the series' "dreamy, romantic vibe" may be off-putting to viewers who discovered Watanabe through his work on Cowboy Bebop, but argued that "to dismiss Kids on the Slope would be a huge mistake.

"[70] Nicole MacLean of THEM Anime similarly concurred that while the series "moves slowly and thus may not gain widespread appeal," its "poignancy and its adept choice of viewpoint as a reflective rather than purely nostalgic show ultimately win out over its mistakes.