Nariyuki has made many relationships throughout the series and gained some affection from the girls.
Initially, Rizu was quite indifferent with Nariyuki and couldn't even remember his name; despite the fact that they are seated next to each other or her being tutored by him for almost a week towards the beginning of the story.
But over time, Rizu began to care and depend upon Nariyuki more, even looking for him first when she was scared.
Nariyuki is tutoring her in Japanese.
Nariyuki knows that she wants to study psychology because of dealing with the weakness of observing competitors' behaviors in games in the beginning.
Rizu has developed romantic feelings for Nariyuki after the accidental kiss in studying camp in Question 14.
He appreciates Rizu's determination for trying to learn psychology. Her mind is changing after the relationship is built, and the motivations of learning psychology are different in recent chapters.
Rizu is the first person who knows his decision of studying education, although she did not reveal to Fumino and Uruka.
Rizu calls Nariyuki "Yuiga-san" in the early chapters and calls him "Nariyuki-san" from the end of summer vacation.
He calls "Ogata" for Rizu.
Initially, Fumino was quite indifferent with Nariyuki, not even remembering his name, despite the fact that they are seated next to each other or her being tutored by him for almost a week towards the beginning of the story.
Nariyuki is tutoring her in mathematics.
Nariyuki knows she wants to study astronomy because of the influence of her late mother in the beginning.
Over time Fumino began to open up to Nariyuki, even becoming his consultant or so-called "sensei" in understanding girl's feelings.
She falls in love with Nariyuki after Summer Festival in Question 39, but does not want to be open. After that, she calls "Nariyuki-kun" naturally.
She kissed Nariyuki (with kigurumi) in drama at the school festival.
Fumino calls him "Yuiga-kun" in the early chapters, and then calls him "Nariyuki-kun" after Summer Festival.
He calls "Furuhashi" for Fumino.
Uruka has known Nariyuki since middle school and enrolled in the same high school because she wants to study with him. She would often ask to copy Nariyuki's homework from middle school, having not done hers due to a preoccupation with swimming.
Nariyuki is tutoring her in English.
Uruka has had romantic feelings for Nariyuki since middle school.
They shared some nostalgic experiences in middle school in the trespass of middle school in Question 43 Uruka confessed to Nariyuki in the swimming pool, but he was unready to understand. Nevertheless, the relationship has had some progress, and he calls "Uruka" naturally.
Uruka kissed Nariyuki because of a misunderstanding of the kiss as greeting in the Western world, due to it normally being on the cheek instead of the mouth.
Uruka calls "Nariyuki" for him.
He calls "Takemoto" for Uruka in early chapters and calls "Uruka" after the trespass of middle school.
Kirisu, being a teacher at Ichinose Academy, is respected by Nariyuki.
At first, Nariyuki was somewhat afraid of Kirisu, due to her cold demeanor, she still does occasionally frighten him. Though over time, Nariyuki comes to realize that Kirisu cares very deeply for her students, wishing to help them as best she can. From this Nariyuki is the first to try and convince the other students that Kirisu is not as cold as she seems to be.
Nariyuki also helps her to clean her room occasionally.
Both are aware of avoiding breaking the teacher-student relationship.
Mafuyu calls "Yuiga-kun" for him, and he calls "Kirisu-sensei" (Miss Kirusu) for Mafuyu.
Nariyuki respects Asumi as his senpai.
When Asumi first met Nariyuki, in a university preparatory school, she thought nothing of him. This changed when Nariyuki stumbled upon her part-time job as a waitress in a maid cafe High Stage. Asumi then made him a promise to tell no one, this led to their relationship deepening and them becoming more friendly with one another; due to this Nariyuki regularly helps Asumi with her studies.
Due to certain circumstances, Asumi lied to her father saying that she and Nariyuki were a couple, in order for her father to not learn of her part-time job. Afterward, she pretends to show love to Nariyuki for her father, and Nariyuki can participate.
Asumi will often tease Nariyuki for her own amusement.
Due to Asumi's teasing, there isn't a clear answer about her feelings towards Nariyuki, although it is quite clear she is at least interested in him.
Asumi calls "kouhai" for him, and he calls "senpai" for Asumi.
Kobayashi is one of the classmates of Nariyuki.
He knows Nariyuki from elementary school and studies in the same class from middle school.
They often play together, and sometimes play in Yuiga's home.
Oomori is one of the classmates of Nariyuki.
He likes to play with Nariyuki, often makes fun of him, but sometimes makes trouble.
They have quite a friendly relationship, often along with Rizu.
She insists to match Nariyuki with Rizu and shows to favorite Rizu instead of Nariyuki.
She is quite unaware of exposing clothes on activities.
Sawako calls him by full name, and he calls "Sekijou" for Sawako.