Isokawa Nina is a half-American half-Japanese girl who is a regular supporting character in the ani-manga series Tona-Gura!. Lonely because of her frequently absent parents, she adores the families of Arisaka Kazuki and Kagura Yuuji. Though the same age and class as Yuuji's little sister Marie, Nina already has a bust size that, relative to her body size, is already almost as large as that of Kazuki's older sister Hatsune. Her personal style of manic energy and agressive affection is the exact opposite of Marie, who she naturally tries to make her instant best friend--the friendship emerges, but it is less than instant.
Even the hormonal Yuuji would not pursue a girl the same age as his sister, but he can't help but notice her figure, a fact that earns him frequent warnings from Marie and Kazuki, and frequent teasings from Hatsune and Suzuharu Chihaya. Doubling Yuuji's awkward stance in this is the enormous crush Nina has on him, though he to his credit takes pains to treat her like a little sister, and in fact she calls him Onii-Chan.