Here is a comprehensive manga synopsis for 3LDK no Ō-sama.

The story is set in a well-located apartment building near the city center, where the heroine Misato’s parents serve as the landlords. Misato finds herself surrounded by several handsome young male tenants, which might sound like a dream scenario, but there is a major catch: every one of them is a shut-in with deep personal flaws. Yamada is an extreme narcissist who lives entirely in his own delusions. Yoshida is a stereotypical otaku who treats a fictional 2D character as his wife. Sasaki is a novelist with a profoundly lazy attitude whose room is piled high with garbage. The daily life of Misato revolves around dealing with these men, who are selfish, oblivious to the real world, and thoroughly useless.

Despite her initial irritation, Misato is forced to take care of them, leading to a series of comedic and awkward situations. Her feelings gradually shift, especially toward Yamada, who happens to be her classmate. Over the course of the manga, Misato begins to see past their flaws, and the relaxed but bizarre dynamic between a tsuntsun girl and a group of handsome hikikomori develops into something more. The narrative unfolds across three volumes, with the final arc increasing the romantic focus, including love events involving the other shut-ins, as Misato comes to terms with her growing interest in Yamada. The series is a leisurely, self‑home romantic comedy that plays on the contrast between a seemingly desirable setup and the exasperating reality of its hopelessly flawed characters.