The first truly global pandemic, the Russian Flu of 1889 lasted until 1895 and current studies seem to identify it as an early covid, very similar to what we have today. It started in Bukhara and spread extremely rapidly worldwide. It reached Japan by early spring 1890.

In Japan it became known as Osomekaze, an old slang for influenza-like diseases. Osome was also the name of the heroine of a hugely famous 1710 play based on a real and very tragic love story that took place in Osaka in 1708. A rich girl, Osome, falls in love with a poor boy.

The boy's name was Hisamatsu, and in 1890 the writer Okamoto Kido (1872-1939) wrote in jest a newspaper column where he suggested people should just tell Ms. Osome that young Mr. Hisamatsu was not in to ward of the influenza. To his surprise, the joke caught on...

...all over Tokyo people started placing notices on their front doors saying 久松るす (Hisamatsu is out), as a good luck charm or talisman. Of course, in 2020 these signs started to go up again. Then as now, people need to joke and make fun of what scares them.

If you want to read something different, I recommend Okamoto's hugely famous 1917 historical detective story "The Curious Casebook of Inspector Hanshichi", a street smart and weary retired old cop retells some of his cases on the beat in Edo, mid-19th century.