Nana Sunohara, younger sister to Ayaka Sunohara, stands 162 cm tall with a slender yet voluptuous figure. She possesses long honey-blonde hair reaching her waist and distinctive amber-yellow eyes. Her tan skin reflects the gyaru subculture, featuring subtle tan lines above her hips suggestive of tanning bed use. Following a three-year time skip, her appearance shifts significantly; she adopts shorter hair and favors more modest clothing like baggy long-sleeved shirts paired with short jean shorts.

Her personality offers a vibrant contrast to her sister's, marked by an energetic, upbeat nature and a constant desire for entertainment. She frequently socializes with friends or Aki Shiina. Despite her lively demeanor, she exhibits notable gentleness, patience, and benevolence, especially in her interactions with Aki. This lively nature is occasionally tinged with mischief, earning her the "little devil" descriptor.

Debuting in the manga's Chapter 17, she appeared in the anime's Episode 1 as a cameo before her full introduction in Episode 6. She is a former resident of Sunohara-sou, having occupied Room 101 prior to Aki Shiina, and was a member of her school's student council as depicted in the anime.

Within the story, Nana frequently engages other characters, particularly through her playful teasing of Aki, which sometimes escalates into physical antics reflecting her boldness. Her relationship with Ayaka highlights their differing appearances and temperaments, a contrast so pronounced it often leads others to question their familial connection.

Trivia notes include the meaning of her name: "Nana" incorporates the kanji for "vegetables/greens" (菜), while "Sunohara" combines "spring" (春) and "field/plain" (原). She also shares a room number legacy with Aki, both having resided in Room 101 at different times.