Hibiki Hanekura (羽倉響, Hanekura Hibiki) is the younger sister of Akatsuki (Shizuka Hanekura). They have a dog named Myojo (ミョウジョウ).
She is first mentioned, although not by name, in volume 5. Akatsuki is beleaguered by her memories of the real world, where she was so short that Hibiki called her the younger sister. It was later specified that Hibiki is 10cm taller than Akatsuki, so Akatsuki usually wore hand-me-down clothing from her younger sister.
It was Hibiki who suggested that Akatsuki be an animal groomer, saying that such a job suited the untalkative Akatsuki.
- "Hibiki" means "echo," which contrasts with Akatsuki's real name, Shizuka, which means "quiet."