On February 12, 1933, Kiyoko Matsumoto, a 19-year-old Japanese schoolgirl, took her own life by jumping into the active volcanic crater of Mount Mihara on the island of Izu Ōshima.

Kiyoko had developed feelings for another student, Masako Tomita, but due to the taboo nature of lesbian relationships in Japanese culture at the time, the two girls decided that Kiyoko should end her life in the volcano's fiery depths, where temperatures can reach 1200°C. Kiyoko ultimately carried out this plan.

Kiyoko's suicide sparked a disturbing trend among Japanese people, and in the year following her death, a total of 944 people, including 804 men and 140 women, jumped into the deadly volcanic crater of Mount Mihara to end their lives. In the next two years, there were an additional 350 reported suicides at this location.

The high number of deaths at this ominous spot was likely due to the allure of following in Kiyoko's footsteps and the perceived romanticism of ending one's life in a volcanic crater.

Some people were drawn by an inexplicable curiosity to witness the tragic events at Mount Mihara, traveling to the site specifically to watch the desperate jumps of those seeking to end their lives. These voyeuristic visitors added to the macabre atmosphere at the site.