Mottainai Baasan
English title: Mottainai Grandma
Japanese title: もったいないばあさん
Type: ONA
Source: Picture book
Episodes: 4
Status: Finished Airing
Aired: Jun 4, 2020 to Jun 25, 2020
Duration: 6 min per ep
Rating: G - All Ages
Studios: LIDENFILMS
Genres: Slice of Life

In the books, the titular Grandma seeks to explore the true meaning of the Japanese phrase "mottainai" after her son asked her what it meant and she couldn't answer. "Mottainai" is a commonly used exclamation that roughly translates to "what a waste!", expressing regret over wastefulness. The Grandma seeks to explore the meaning and importance of "mottainai" in the story.

(Source: Anime News Network)