Kusano (草野, Sekirei #108), commonly referred to as "Kuu-chan" or "Ku", is the youngest of Minato's Sekirei, and is also known as the "Green Girl" (緑の少女 Midori no Shōjo) by other Sekirei. At the beginning of the story, she was hiding in a botanical garden after being traumatized when Mikogami attempted to forcibly wing her. Kusano communicated with Minato telepathically and led him through the garden until he found her. Kusano refers to Minato as Onii-chan (big brother), and is the most attached to him. She does not like fighting or quarreling and she can be seen stopping them when they start. She is also very impressionable and often copies Musubi, Tsukiumi and Kazehana's mannerisms. She VERY much wants to be Minato's wife when she grows up, and is highly possessive of him at times, even biting her fellow sekirei when they start to get too close to him.
Kusano has the power to control plants, making them grow at an accelerated rate and to unnaturally large proportions, and typically uses them to ensnare or disable her opponents without hurting them. Her uses of various plants is highly imaginative and extremely effective. Her MBI adjustments were never completed, which is why whenever she's sad or upset, her powers rage out of control. She has a sibling-like relationship with #107 Shiina despite the fact that his power is the natural opposite of hers. In the manga, when Minato initially brought her to Izumo Inn, Miya drew and pointed a sword at Minato's face, believing that he had kidnapped her. Her name literally means "A Grass Field", and Miya's nickname for Kusano is "Adopted Child".