Emergence (Henshin in Japanese), also known as Metamorphosis and 177013, is a hentai manga by artist ShindoL, which gained much notoriety online for its depressing, grimdark storyline. The story is often referred to by the number "177013" in reference to its assigned page number on the hentai database nhentai.net.
Emergence originally ran from July 26, 2013, to March 26th, 2016. In November of 2016, the series was collected for digital publication in English under the title Metamorphosis. The plot follows a teenage girl named Saki who transforms from a nerdy introvert into a drug-addicted, homeless prostitute.
On May 2nd, 2016, YouTuber lolicide uploaded a video titled "The Citizen Kane of Hentai" (shown below). Within 17 months, the video gathered upwards of 22,300 views and 170 comments. On May 19th, a post about the Emergencewas submitted to /r/hentai, which described it "quite honestly the most depressing thing I've ever read."
On June 5th, a thread about the hentai was submitted to the /h/ (Hentai) board on 4chan. Several other threads were submitted to 4chan discussing the hentai over the next several months. On December 25th, 2016, FunnyJunkuser aznzeus posted an image macro featuring before-and-after illustrations of the character Saki (shown below).
On May 1st, 2017, YouTuber akidearest uploaded a vlog featuring her thoughts on the manga titled "Why This Manga Was So Difficult For Me" (shown below). Within five months, the video gained over 440,000 views and 2,300 comments.