"Kyosuke Yokoyama is a main character in the Japanese manga series ""Petty Relationship"". He is a high school student who comes from a wealthy family and is known for his handsome looks and charming personality. Kyosuke is a self-confident and ambitious individual who always strives for success in all areas of his life.

Kyosuke is initially introduced as the classmate and neighbor of the series' protagonist, Ayumi Kohinata. He takes an immediate interest in Ayumi and begins to pursue her, despite her declining his advances. Kyosuke's persistence leads Ayumi to adopt a more assertive attitude towards him, and the two eventually enter into a complicated and tumultuous relationship.

One of Kyosuke's defining traits is his manipulative nature. He is shown to be adept at manipulating those around him in order to achieve his goals. He frequently puts on a facade of charm and kindness to gain the trust and admiration of others, but underneath lies a shrewd and calculating personality.

Despite his flaws, Kyosuke is a complex and multi-layered character who is intrigued by the unpredictability of relationships. He is depicted as someone who is often torn between his desire for control and his fear of being vulnerable. This internal conflict is highlighted through his relationships with both Ayumi and his father, who is also shown to be a domineering figure in his life.

Kyosuke's character arc throughout the series is focused on his growth and self-discovery. He learns to confront his inner demons and accept his own weaknesses, ultimately becoming a more empathetic and self-aware person. Overall, Kyosuke Yokoyama is a compelling and dynamic character whose journey is one of the main draws of ""Petty Relationship""."