The successful academic, Kaoru Nishimi, transfers to a new school in Kyushu, Japan, where he meets the delinquent, Sentaro Kawabuchi. Despite their vastly different personalities and backgrounds, they bond over their shared love of jazz music and form a friendship. The two boys, along with their classmate Ritsuko Mukae, start a jazz band and practice together in the basement of a record shop owned by Ritsuko's family.
As they play together, Kaoru begins to open up to Sentaro and the other students at their school, revealing his painful past and struggles to connect with others. Sentaro, on the other hand, starts to show a softer side as he helps Kaoru overcome his social anxiety and learns to express himself through music.
The group faces various challenges, including personal struggles and conflicts with other classmates, but they persevere and continue to play jazz together. Along the way, they discover the power of music to bring people together and the importance of accepting others for who they are.
Kids on the Slope is a coming-of-age story about friendship, music, and the journey towards self-discovery. It explores themes of identity, acceptance, and the transformative power of art.