"Onii-chan Dakedo Ai Sae Areba Kankei Nai yo ne" centers on the lives of Akiko Himenokōji and her older brother, Akito Himenokōji, who reunite after years of separation. Akiko, a high school student, moves into the Himenokōji household, which also includes Akito and their other siblings. The story explores their daily lives, blending comedy, romance, and slice-of-life elements. Akiko harbors romantic feelings for Akito, which she struggles to reconcile with their sibling relationship. Akito, on the other hand, is protective of Akiko but remains oblivious to her deeper emotions.

The narrative unfolds through a series of comedic and heartfelt interactions, often highlighting the eccentricities of the Himenokōji family. Akiko’s attempts to express her feelings are frequently thwarted by misunderstandings, Akito’s dense nature, and the interference of other characters, including their siblings and friends. The series also introduces additional romantic subplots involving other characters, adding layers to the central dynamic between Akiko and Akito. Themes of familial bonds, unrequited love, and personal growth are woven throughout the story, creating a balance between lighthearted humor and emotional depth. The manga maintains a focus on character development, exploring how each individual navigates their relationships and aspirations within the framework of their unique family dynamic.