Hiromi Kuroki

Height: 169 cm (5'5")

She is a childhood friend and fellow native of the same hometown as Maron Yanagihara. According to Maron, "Kuro-chan is cool and composed, yet kind; I want to stay close friends with her forever."

Although she appears cool, she tends to get intensely fixated on things once she takes an interest; for instance, a childhood tour of a soy sauce factory got her hooked on making her own soy sauce, and seeing a diesel locomotive sparked a hobby of tinkering with machinery. Perhaps due to this nature, she was once unsure of her future path during junior high; however, after meeting Mashiro Soya at the Blue Mermaid Festa and the entrance exam venue, she developed a strong admiration for her and resolved to become a Blue Mermaid herself. Incidentally, Maron gets jealous, fearing that "Kuro-chan might get snatched away by some random girl."

Beyond general machinery, she possesses deep knowledge regarding fuels, lubricants, and explosives.

After enrolling, she was delighted to be assigned to the same ship—the Harekaze—as Mashiro, but she openly expressed dissatisfaction and jealousy over the fact that Akeno Misaki, rather than Mashiro, served as the ship's captain.