Koharu's Father, known as "Koharu no Chichi" or "Koharu's Dad," operates the family liquor store Hidaka Mart. He sports gray hair and distinctive glasses with swirl patterns, typically dressed in a light blue buttoned shirt, green vest, red-brown pants, and brown shoes. His personality blends energy and a laid-back nature, demonstrating strong family support through granting Koharu freedom and purchasing items for her happiness. He is a diligent worker prioritizing his family's well-being.

His significant actions start with installing arcade cabinets outside Hidaka Mart as a profitable investment, facilitating Koharu's initial encounters with Haruo Yaguchi. Later, he interrupts Haruo and Koharu's Christmas party plans by delivering a new arcade game—King of Fighters '94 in the manga or Street Fighter II in the anime—which captivates Haruo, causing him to stay. He subsequently alerts Koharu that Haruo is playing outside during a blizzard. In another instance, he buys a Super Nintendo (SNES) for Koharu to encourage Haruo's visits. While gaming with her, he discovers the SNES version of Final Fight lacks co-op functionality. Beyond these events, he primarily appears in background scenes or brief mentions.

In *Hi Score Girl Dash*, he makes a cameo assisting a customer at Hidaka Mart. His relationship with Koharu is positive, built on trust and encouragement of her interests in video games and potential romance. He supports her decision to live at home into her late twenties. His interactions with Koharu's mother reflect a mutually caring partnership focused on their daughter's welfare.

The surname "Hidaka" (日高) translates to "sun high." His background beyond shop management and family life remains unelaborated.