Otaku no Shiro

The god writer she admires is the grandson of her late otaku friend! Hami, a nerdy college student, is forced to live alone after her sister gets transferred to a new job. Then, Hami's follower "Sakurako" passes away! Hami receives a dreamy mansion filled with otaku goods from her otaku friend and the chairman of a large company in her will, and she will be living with her three grandchildren...! The life of an otaku girl and her three brothers is about to begin! Source: Mangadex