Otaku Baa-chan
オタクばあちゃん · おたく ばあちゃん
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
A slice-of-life about a grandma who had been captivated by 2D characters and became an otaku even after turning 80, and her grandson who kindly watches over while trying to keep a straight face! A host and a high school student are also involved, are they going to show off their otaku power...!? (Source: Kadokawa, translated) Note: Includes 1 extra chapter.
Source: AniList
External databases: AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections