Earth-chan is an anime-style anthropomorphic representation of the planet Earth. She is depicted as a young girl with hair dyed in the colors blue and green, resembling a photograph of the planet taken from space. Online, image macros featuring the character often contain jokes using the popular anime trope of characters being insecure about their flat chest by referencing to the flat earth theory.
On November 30th, 2017, Twitter user @Trinimmortal tweeted a joke about creating an anime featuring the planets of our solar system as anime girls, which would contain a running gag about Earth-chan saying “I’m not flat!” On December 4th, Twitter user @felipecunhaeloi responded to the tweet with an illustration of the anime idea (shown below).
On December 7th, DeviantArtist DatWeirdoWhoLuvsMilk posted several illustration of Earth-chan wearing a surgical mask (shown below).
On December 10th, 2017, Redditor M4DHouse submitted an image macro with the caption “When someone says Earth-Chan is flat,” followed by a screenshot of Mafuyu Hoshikawa from Blend S saying “It seems you require a hard education” (shown below).
On December 12th, 2017, Redditor WatBoi19 submitted an illustration in which the Earth-chan character complains to a man wearing a NASA shirt that “everybody call me flat,” leading the man to say “Don’t believe what they said, senpai. You are not flat!” (shown below). Within 24 hours, the post gained over 5,900 points (93% upvoted) and 280 comments on /r/animemes.