Katana are traditional Japanese swords originally wielded by samurai in feudal Japan. Online, the weapons are often associated with White enthusiasts of Japanese culture, who are mockingly referred to as neckbeards and weeaboos.
Katana were first produced in the Muromachi period in feudal Japan, and have been a mainstay in Japanese weaponry since. In July 2009, a copypasta story about the fictional character Ken-Sama, an adult American male obsessed with Japanese and Otaku culture, began circulating on 4chan's /jp/ (Otaku culture) board. In the copypasta, Ken-Sama claims he trains with his katana every day:
"I train with my Katana every day, this superior weapon can cut clean through steel because it is folded over a thousand times, and is vastly superior to any other weapon on earth. I earned my sword license two years ago, and I have been getting better every day."
Starting in 2009, YouTuber bbillyk began posting videos of himself cutting water bottles in his backyard with a katana. On October 7th, 2012, YouTuber goosmurf uploaded a montage of clips featuring YouTuber Will Keith slashing water bottles with his katana (shown below). On June 27th, 2013, Redditor wolfhowler submitted the compilation to /r/IdiotsFightingThings. Within four years, the video gathered upwards of 3.09 million views and 11,200 comments.
On April 15th, 2015, Tumblr user nunchler published a post highlighting several photographs of men wearing fedoras while holding katana (shown below). Within two years, the post gathered upwards of 1,700 notes. On July 6th, Reeditor river710 submitted a copypasta story titled "unsheathes katana" to the /r/copypasta subreddit.
On December 26th, 2015, YouTuber Papa Smeep uploaded a clip of a news segment about a man who defended a man from attackers on a train titled "Cringe Weeaboo Defends Man on Train with Katana" (shown below).
Katanas are Underpowered in D20
Glorious Nippon Steel Folded Over 1000 Times
"Glorious Nippon Steel Folded Over 1000 Times" is an ironic catchphrase use to impersonate and mock individuals who think katana are vastly superior to western weapons. The catchphrase is often associated with a captioned gif from the videogame War Thunder, featuring a plane cutting a wing from another plane (shown below).
"Sword Practice" is a video in which a young man demonstrates how to perform various katana moves in his front yard. While the original video has been removed, a mirror uploaded by YouTuber Nigel Nuttcrusher video blog in January 2010 received more than 100,000 views and 400 comments within six years (shown below). Additionally, several remixes of the video have been posted on the video-sharing site.
I Studied the Blade
"While You Were Partying, I Studied the Blade" is an expression used in copypastas accompanied by photographs of men wielding katana, in which they mock peers for attending social gatherings while they train sword fighting. On April 9th, 2016, Redditor ktron24 submitted an image macro captioned with the phrase to /r/justneckbeardthings (shown below, left). On June 3rd, Redditor graysjsnake posted a screenshot of a Facebook post featuring a variation of the copypasta to /r/justneckbeardthings (shown below, right).
 /r/OutOfLoop – Origin of Glorious Nippon Steel, folded over 1000 times?