Kazuya Takamori is Suzume Imamura's boyfriend. He endured profound neglect as a child due to distant, wealthy parents who rarely returned home and offered minimal interaction during their infrequent visits. This isolation drove him to seek companionship outside the family, though he understood his parents prioritized their own lives. Emotional struggles eventually erupted into delinquent behavior, including violence and bullying, as he sought acceptance and control. This downward spiral culminated in intense feelings of worthlessness and a suicide attempt by plunging into a canal.

Suzume Imamura physically intervened during this attempt. Her actions became a defining moment for Kazuya, who perceived her as the supportive presence he had always needed. This encounter radically shifted his outlook. He developed a deep appreciation for existence and formed a devoted bond with Suzume. He particularly values her consistently cheerful personality, which others sometimes find annoying. Their commitment is symbolized by a ritualistic "marriage" ceremony crossing a river together, demonstrating their pledge to face life's obstacles as a couple. This involved swimming across a canal while holding hands and using a floating tube; Suzume briefly lost her grip and faced danger before Kazuya rescued her. The act drew public attention and involved school officials, but they faced the consequences united.

Following this transformation, Kazuya abandoned his delinquent behavior and focused intensely on academics. Despite his previous reputation, he rose to the top academic standing in his grade and gained admission to a prestigious high school. He is also noted for being regarded as the best-looking in his grade. His relationship with Suzume remains central, characterized by ongoing care and mutual support. Later interactions show him expressing concern for Suzume's well-being, such as warning her about potential injuries, and racing to her aid when she falls and sustains a bloody nose. His protectiveness and affection toward her continue to define his character beyond their initial struggles.