"Danchigai" is a slice-of-life comedy anime centered around the daily lives of the Nakano siblings, who live together in a small apartment building. The story primarily revolves around Yūsuke Nakano, the only brother in a household of five siblings, and his interactions with his four sisters: Mutsuki, the eldest and most responsible; Kōsuke, the tomboyish and energetic second sister; Satsuki, the quiet and reserved third sister; and Uzuki, the youngest and most mischievous. Each sibling has a distinct personality, which leads to humorous and heartwarming situations as they navigate their everyday routines.

The narrative unfolds in a lighthearted manner, focusing on the siblings' playful banter, sibling rivalries, and moments of familial bonding. Yūsuke often finds himself at the center of his sisters' antics, whether it's Mutsuki's overprotective nature, Kōsuke's competitive streak, Satsuki's shy yet thoughtful demeanor, or Uzuki's relentless teasing. Despite their differences, the siblings share a close-knit relationship, and their interactions highlight the dynamics of a large family living under one roof.

The series is episodic, with each episode presenting self-contained stories that explore various aspects of the siblings' lives, such as school, hobbies, and personal quirks. The humor is derived from the exaggerated yet relatable scenarios that arise from their interactions, such as Yūsuke's attempts to maintain his privacy or the sisters' collective efforts to embarrass him. The tone remains consistently light and comedic, with occasional moments of warmth that underscore the familial bond between the characters.

The apartment building itself serves as a central setting, with its compact layout emphasizing the close proximity of the siblings and contributing to the comedic tension. The series also introduces a few recurring side characters, such as the siblings' neighbors and classmates, who occasionally add to the chaos or provide additional comedic relief. Overall, "Danchigai" offers a charming and humorous portrayal of sibling relationships, capturing the joys and challenges of living in a bustling household.