Nobu has an affectionate nature, and exhibits protective behavior over both Risa and Nakao. Because of this affection for Risa, Nobu frequently lashes out at Ōtani for being inconsiderate towards Risa's feelings and equally lectures Risa for allowing herself to be put in frustrating situations. Her behavior towards Nakao is vastly different than it is towards any other character, full of loving words and baby talk. Nobu is very refined around her family and worries greatly for her grandmother's health, even going as far as moving to Hokkaido with her after high school despite this putting strain on her relationship with Nakao.
Nobu is a short and busty girl, unlike her best friend Risa. She wears extremely stylish clothing when not in her uniform, these outfits are often picked out and styled by Risa. Nobu's short wavy hair is usually worn down with two small braids framing her face, but she will occasionally tie her hair up in a ponytail or two side buns.
In the anime, Nobu has dirty blonde hair and brown eyes. Nobu wears a school uniform consisting of a white dress shirt, gray skirt, blue knee-high socks with white stripes, a red ribbon, pink flats, and accessorizes with various bracelets. During warmer weather she wears a peach sweater vest with a red stripe and star, and a peach cardigan with red stripes on the arm, red buttons, a red star, and a red loose fitting ribbon during colder weather.
In the manga, Nobu has orange hair and reddish-brown eyes. Unlike her friends, Nobu refuses to wear her uniform during school events and has even gotten in trouble by her teachers for it despite Maido Academy being a uniform optional school.
- Heikichi Nakao: Nakao is Nobu's boyfriend from before the series began. Nobu claims they started dating due to their known mutual interest in each other. The story goes that in their last year of junior high together, Nobu said, "I wish I had a boyfriend like Nakao," and Nakao reciprocated with, "I wish I had a girlfriend like Nobuko" and the rest was history! Nakao and Nobu are extremely loving and affectionate towards each other.
After Nobu had confirmed her plans to move to Hokkaido with her grandmother after graduation, Nakao started to act strangely. Nobu eventually overheard Nakao saying that he did not want Nobu to leave for Hokkaido but was too nervous to tell her because he did not want to hold her back from what she wanted to do. This caused strain between the couple and Nakao tries to get Nobu to break up with him by pretending to be a player and cheater. Nobu knows what he's doing and doesn't break up with him, but confirms her decision to go to Hokkaido which shows Nakao that he is not holding her back in any way. They maintain a long distance relationship after graduation.
- Risa Koizumi: Risa and Nobu met their first year of high school (equivalent of 10th grade) and have been best friends ever since. Risa considers Nobu to be her older sister figure since she is the most mature and wisest about relationships, and is older than Risa. Risa often asks for Nobu's advice on how to confront Ōtani about her feelings and later regarding her relationship with him. Nobu is greatly disgusted by some of Risa's habits, like her obsession with Cain-sama and later Maity-sensei.
- Chiharu Tanaka: Chiharu and Nobu met their first year of high school (equivalent of 10th grade) through their mutual friend, Risa. Chiharu is often by Nobu's side quietly supporting her advice to Risa and sometimes even calming Nobu down when she gets angry.
- Atsushi Ōtani: Ōtani has known Nobu since junior high. Nobu is easily irritated by Ōtani's idiocy when it comes to his relationship with Risa and his overall arrogance. She has a lot of fun picking on him for just about everything he does.
- Ryoji Suzuki: Suzuki and Nobu met during remedial summer classes during their first year of high school (equivalent of 10th grade). Suzuki is the boyfriend of Nobu's close friend, Chiharu. She doesn't speak much with Suzuki, but still considers him a close and trusted friend.
- Seiko Kotobuki: Seiko and Nobu met when Seiko briefly dated Ōtani. Nobu did not initially like Seiko because she got in the way of Risa's chances with Ōtani. Seiko and Nobu eventually formed a friendship after Ōtani and Risa started dating, and enjoy's talking to her about fashion.