Yūto is the main protagonist of the story. He is an ordinary student who attends the private high school Hakujō Academy and is in his second year of high school. One day, he stumbles across his classmate Haruka in the library and discovers her hidden secret—she is a major otaku and loves anime and manga. Following this revelation, Yūto starts to hang out with Haruka which brings up the envy and jealousy of many of his fellow classmates. Yūto lives with his parents and older sister Ruko, though his parents are always working and thus are generally absent from home. He behaves bluntly and generally likes to be left alone. He has an average determination to study for school. Even though he and Haruka are dating, he sometimes believes since he is not wealthy he cannot officially be her boyfriend.
Haruka is the main female character of the story, and is Yūto's classmate. She is idolized at school due to her beauty and intelligence, and is regarded as the school's most unattainable girl. In fact, at school she is known by the French nicknames "Nuit Étoile" (The Night Star) and "Lumière du Clavier" (The Piano's Light). She is very skilled at playing the piano and has taken overall victories in international contests. She also has a gentle personality, is a natural airhead, and is quite clumsy. Her deep hidden secret is that she is a major otaku and loves anime and manga. In middle school, her secret was exposed and she received a certain amount of prejudice towards it which caused her to keep it a secret once she entered high school. When Yūto finds out about it, Haruka is relieved that he does not tell anyone or harass her about it. She also comes from a rich family and privileged upbringing, so her interest in the otaku subculture is looked down upon due to her status in society, which is another reason why she keeps it a secret. Haruka once fled to a park after being scolded by her father, several years before. It was here that her anime obsession started when Yūto gave her the first issue of Innocent Smile. While being very talented, she cannot draw well, but does not realize it because she is too proud of it for anyone to tell her directly.
Nobunaga is a childhood friend of Yūto who attends the same private high school, though is in the class next to his. He has a cheerful and openhearted personality, gets very good grades, and is considered a bishōnen by the female students. However, he is a hardcore otaku and is familiar with the layout of Akihabara. He is extremely famous in various places in Akihabara. Due to his enormous amount of purchases, he is known as "Kaiser" at the Animate store, and is one of three people who possesses the golden Animate card. At a maid café where Haruka once worked part time called "@Home ~Café", there is a picture of him shaking hands with the manager of the café, framed in gold with the caption "Welcome home, our greatest master" hung in the center of the café.
Yukari (light brown hair, braided) is the vice-homeroom teacher to Yūto's class and is an old friend of Ruko. She is referred in the story by Yūto as the "sexual harassment teacher". She is constantly smiling, though she enjoys teasing trouble makers. She likes spending a lot of time over at the Ayase house, and is unmarried though wants a boyfriend. At school, she is in charge of teaching music. She is twenty-three years old, though refers to herself as "eternally seventeen". There is a possibility that she is the rumored teacher that graduated from this same school and famous in the music world as the "Performer of the Sunset".
Shiina is a girl who participated in the London Piano Contest with Haruka; Shiina ranked second before Haruka who ranked first. She transfers into Yūto's class at school. Her hobbies include playing the piano and the martial art of naginatajutsu. She always has a positive, cheerful and sociable personality. This makes her transition as a transfer student very easy. She used to live in Otaru, Hokkaidō, Japan, though does not speak much of those days. She shows an interest for Yūto as she believes there might be a reason they constantly bump into each other. She said one of the reason she chose Yūto's school to transfer to is because of a famous teacher who graduated from the school and is known as the "Performer of the Sunset" is teaching at the school.
Tōka is a student at Yūto's school, though she is in her first year, class three. She is known by the nickname "Princess Blizzard" at school due to her domineering and arrogant personality. She comes from a very rich family that is rivaled by that of Haruka. Her family is known as "The East Nogizaka's House and the West Tenōji's house". Yūto worked as her personal butler for one week before Christmas to earn money for Haruka's Christmas present. After the head of the family died at age 147, she became the third in line to inherit the family fortune. Her ultimate goal is world conquest. She cameos in the first season of the anime adaptation, but is fully shown in Purezza.
Mahiro is Nobunaga's younger sister. She is referred by her brother as a hopeless person with a poor sense of direction. She views Nobunaga as an idiot older brother, though she does like Yūto. She dislikes her brother's otaku hobbies. She does not make an appearance in the anime.
Keiji is Yūto's classmate; he is known as "mad dog". He calls himself a "natural enemy of Akiba-kei, though Yūto has seen him in Akihabara and at Comiket. He originally comes from Shaa's other manga series Kyōhaku Dog's. He only cameos in the anime.
Setsuna is a girl in Yūto's class; she is known as "faithful dog Hachikō". She is considerably clumsy. She has been seen by Yūto together with Keiji in Akihabara and at Comiket. Like Keiji, she originally comes from Kyōhaku Dog's. She only cameos in the anime.
Ruko (black hair, ponytail) is Yūto's older sister. She works as a private secretary to a company president. She is skilled in karate and is a 2-dan. She is a hard worker, though she drinks a lot at home and is unable to do any housework which makes Yūto in charge of all the chores. She generally has a rough attitude and will often speak in a brutish manner. Since her parents are absent so often, Ruko takes up the position as the highest person in the house with her brother. When first meeting Haruka, Ruko was very pleased with her, though Yūto regarded this as unusual. She is a weapon fanatic, which is proven by the fact that she owns many magazines about weapons. She also has her personal favorite Japanese blade called "Ruri Dokuro", which means lapis lazuli skull. Her battle skills are considered on the professional fighter level. This is demonstrated when she completely broke the Tennōji's household security with Yukari looking for Yūto when he had to stay one week for his butler part time job and forgot to make food for them.
Mika is Haruka's younger sister in her second year of junior high school. Her hobbies include playing the violin, playing squash, caring for wild pigs, and spying on her sister and Yūto. She has a personality that is exactly opposite her sister, who is naïve. She enjoys Yūto's company and she often calls him "Onii-san" (an affectionate word meaning brother, brother-in-law, or a brother-like male figure). When Haruka is with Yūto, however, Mika likes to tease them. In contrast to her airhead older sister, Mika is very stable. Even at her young age, she is more knowledgeable about sex than Haruka, although she will get shocked or stunned mentally if exposed to H-rated material just like her sister. She shows some interest in Yūto after their date. She is deathly afraid of ghosts. She has been running for the student council president of her all girl school for two consecutive years. She is just as much as an idol as her sister at school and is known by the name "Moonlight Strawberry".
Gentō is Haruka's and Mika's father. His last name is adopted from his wife's family. His speech and conduct makes him seem like a member of the yakuza, though he is a loving parent who dotes on his daughters. He even bought an entire island for Haruka's birthday. He is against Haruka hanging around Yūto so much, though he does not mind having Yūto around when he is alone. He heads the family's private paramilitary strike force unit known as the Hell Hounds.
Akiho is Haruka's and Mika's mother. Despite having given birth twice, she appears youthful and beautiful; Yūto originally thought she was Haruka's older sister or cousin when he first met her. She is a principal of a cooking school. She has a quiet and intellectual demeanor but has the strength to overcome her husband; in fact, she is referred to by Yūto and Haruka as "Nogizaka house's ultimate weapon". In contrast to her husband, she thinks it is good that Haruka and Yūto spend time together, and she likes to watch the development of their relationship by joining in on spying on them. However, she is very strict that Haruka keeps up her studies.
Ōki is Haruka's and Mika's grandfather on their mother's side. He has a sociable personality and is a goodhearted old man. Although he is retired from his original position as the president of the Nogizaka's organization and became the consultant, he is still a very powerful man in the economic and political world. If he wants, all great leaders in the world will gather at one place for a high level conference within three hours. He has a shadow warrior name Heizō Sebastian Sakurazaka, who is Hazuki's grandfather.
Hazuki is the head maid of the Nogizaka family. She is mainly in charge of looking after Haruka and Mika, particularly Haruka; Hazuki acts in the way of an older sister towards her. She is generally very reserved and expressionless, but sometimes speaks of bombshell announcements. Hazuki adores cute things and even has a collection of stuffed animals. She often appears out of nowhere holding a chainsaw.
Nanami is the third-highest ranking maid of the Nogizaka family, and she usually helps Hazuki with her work, but is more commonly found by Mika's side along with helping and joining in on her spying missions. She has a friendly personality and smiles a lot, though also has a wicked tongue. She is seen wearing sunglasses often. Like Hazuki, she also often appears out of no where, though holding a large hammer. She has a habit of driving extremely fast, but Hazuki just states she is a great driver when one is in a hurry.
Ayame, Sara, and Juri are three sisters who are all equally ranked the seventh-highest maids of the Nogizaka family. They are in charge of being chauffeurs to the family. The eldest sister Ayame flies an eight-passenger airplane, which is comfortable to ride. Sara, the middle sister, is very speedy when flying her plane, or driving her limousine, or her stealth fighter plane. Juri, the youngest sister, also flying a plane.
Alister, otherwise known as Alice, is the eight-highest ranking maid of the Nogizaka family, and is in charge of security. She looks like a grade school student, and is a blond Caucasian (most likely German, since she once utters "Bruder", which conveys the same meaning as Mika's "Onii-san", when addressing Yūto). She rarely speaks in the novel (being not yet skilled in Japanese), and normally converses with others via an array of nods and head-shakes to express her meanings.