Sentarou Kawabuchi (川渕 千太郎 Kawabuchi Sentarō) is a deutragonist of the Kids on the Slope series. He is a jazz drummer who refuses to acknowledge other genres of music, a high school student and a delinquent, who often gets in fights.
Sentarou is pale-skinned young man with short, spiky hazel hair, brown eyes, a strong jawline, a muscular frame and a small 'X' shaped scar under his left eye. He is sometimes seen with an adhesive bandage over his nose, and/or his left eyebrow.
Sentarou is the child of an American soldier and a Japanese mother. It is later revealed by his grandmother that his mom had left him with her family. Because of this, he is shunned by his grandmother. He is then raised by his uncle and aunt whom he regards as his father and mother. However, this story is untrue, as the priest at the chruch tells Karou more about Sentarou's background after his disappearance. He states that Sentarou was abandoned at the church (thus the reason his birthday is on Christmas day.) until he was three years old. The story about Sentarou's uncle and aunt taking him in was just a lie to convince his grandmother to let Sentarou stay with them. The reason for this is because his grandmother hates the Americans. Though the priest says the story could be true, as Sentarou's father's sister had worked with the Americans, and had gone missing a few years before Sentarou was found. Despite this, no one knows the truth.
- The name Sentarou means "thousand" (千) (sen), "thick, big" (太) (ta) and "son" (郎) (rou).
- Sentarou's surname Kawabuchi means "river, stream" (川) (kawa) and possibly "edge" (渕) (buchi).
- Sentarou is usually referred to as Sentarou, but he is also known infamously as "East High's Kawabuchi".