1. 1932 Tokyo Fire and Women's Panties
On December 16, 1932, the eight-story Shirokiya Department Store caught fire in Tokyo, leading to 14 deaths. Rumor has it that saleswomen in kimono were forced onto the roof and refused to jump into safety nets held by firefighters out of fear of exposing themselves. Traditionally, women did not wear undergarments with their kimonos.
It is believed after the incident, the store management ordered all saleswomen to wear undergarments with their kimono, and this practice would slowly spread across Japan. However, despite the prevalence in textbooks, this notion has never been proven true. In fact, it has recently been believed that the myth was spread by European news outlets.
2. Cursed Kleenex Commercial
In 1986, Kleenex released three commercials exclusive to Japan. As you can see in the above ad, many viewers found them to be unsettling, and a number of "curses" began to circulate.
Rumors began that the song "It's a Fine Day" was German curse (despite being sung in English), and it led to crew members meeting untimely deaths. The biggest incident would happen to the lead actress in the ads, Keiko Matsuzaka. She would go on to die, or be institutionalized, or give birth to a demon child. None of those actually happened, as Keiko still acts today.
3. Red Room Curse
The legend is based on an interactive Flash horror animation. An internet pop up will appear on your computer, and a recording will ask "Do you like the red room?" Even if you close the pop up, it will keep reappearing until the recording finishes asking the question. Shortly after, the viewer will be killed and their room will be painted red with their own blood.
The urban legend gained notoriety after it was discovered that the schoolgirl who committed the Sasebo Slashing had the Flash animation in her favorites on her computer.