Hiroshi Nonomura is a character from the Cream Lemon series, primarily appearing in the storyline centered on Ami, including the final installment Tabidachi: Ami Shuushou. He is introduced as Ami Nonomura's stepbrother, and both attend middle school in Japan. Physically, he is described as having black hair and blue eyes.

Hiroshi's role in the narrative is fundamentally defined by his secret and intimate relationship with his stepsister, Ami. This relationship is a central, driving element of the story's conflict. The affair begins with a sexual encounter between the two that takes place while Ami's mother is away on a business trip. Their actions lead to significant consequences when Ami's mother discovers the nature of their bond. In response, she sends Hiroshi away to study in London, forcibly separating the pair. This separation has a profound and negative impact on Ami, plunging her into a state of deep depression.

Hiroshi's motivations and inner feelings are revealed more fully later in the story. After a period of absence, he briefly returns to Japan. During this visit, he tells Ami that their romantic relationship must end. However, his true, unresolved feelings are suggested through a discovery Ami makes. While searching for belongings in his room, she finds a book titled First Love. Inside is an old photograph of herself accompanied by a handwritten note from Hiroshi that reads, "If Ami weren't my sister...". This note serves as a critical turning point, indicating that despite his words, his emotional attachment to her persists and he has never fully let go of his feelings. This unresolved tension ultimately motivates Ami to abandon other plans and travel to London to confront their relationship directly, seeking to resolve the complex situation that defines both their lives.