He is Akane Sakumori's classmate and natural adversary. He frequently argues with Akane and struggles to get along with her. Despite being highly intelligent and achieving top grades, he often exhibits unconventional behavior and tends to be absent-minded. He marries Akane to take over his grandfather's Houjou group.
Saito is a young man of average height of 175 centimeters, with a lean build and short black hair. He typically wears the standard school uniform.
Saito is most of the time laid back and calm, sticking to his own space. A slacker by nature, Saito rarely exerts himself, and has a rather extreme minimalist disposition; limiting his dietary habits to nothing but cup noodles, vegetable juices and protein shakes while also being generally very unhygienic, not bothering to wash dishes until they piled up, taking garbage out once per month, and even questioning the need for bathing.
Despite of his laziness, however, he always scores first place in exams, meaning he's academically competent and intelligent enough that he doesn't need to study, due to him being born with photographic memory. Saito in fact loves gaming and has a liking for horror games.
It is hinted that he picked some of his habits as a result of his parents abandonment and emotional abuses, while not fully adjusting to life with his extravagant grandfather. When Akane prepared him proper food, he was delighted at eating something normal, which meant a lot to him, showcasing a degree of loneliness.
More than Saito desires to inherit the Houjou Group, putting up with his grandfather's unreasonable demands.
Though generally composed, his interactions with Akane easily put him into defense mode and bickering. Nonetheless, his daily life with her forces him into a bit of reintrospection, and be more cooperative.
Saito was born with photographic memory inherited from his ancestors, as a result, he was heavily neglected by his parents who were exiled from the Houjou family. Once his grandfather learned that Saito is not a ordinary child, he immediately groomed him to become his successor of the Houjou Group, separated him from his parents in order for him to stay with Shisei's family.
(Source: I'm Getting Married to a Girl I Hate in My Class Wiki)
