"Onii-chan Dakedo Ai Sae Areba Kankei Nai yo ne" centers on the lives of Akiko Himenokōji and her older brother Akito Himenokōji, who were separated during childhood due to their parents' divorce. After years apart, Akiko moves in with Akito, reigniting their sibling bond. However, their relationship takes an unconventional turn as Akiko harbors romantic feelings for her brother, despite societal norms and familial boundaries. Akito, initially unaware of her feelings, struggles to navigate their dynamic while maintaining a sense of responsibility as her guardian.

The story explores themes of familial love, societal expectations, and the complexities of human emotions. Akiko’s bold and straightforward personality contrasts with Akito’s more reserved and cautious demeanor, creating a dynamic interplay of tension and humor. Supporting characters, such as their childhood friend Arashi Nikaidō and Akito’s classmate Ginbei Haruomi, add depth to the narrative by introducing external perspectives and complicating the central relationship.

The plot unfolds through a series of comedic and dramatic moments, blending lighthearted interactions with moments of introspection. Akiko’s persistent attempts to express her feelings and Akito’s internal conflict form the core of the story, while secondary characters provide subplots that enrich the overall narrative. The series balances humor with emotional depth, addressing the challenges of unconventional relationships within a familial context.