Amabie

Amabie is a mermaid or merman with three legs in Japanese myths. It is believed that it will emerge from the sea and make prophecies about harvest or epidemic.
Legend.
It is believed that an amabie appeared before a officer and gave a prophecy that good harvest will get for six years, if disease spread draw its picture and show to the people affected by disease and they will be cured. Believers argue that similar events are reported in different places also. 
COVID-19.
During the COVID-19 pandemic, amabie become popular in Twitter in Japan. Manga artists (e.g., Chica Umino, Mari Okazaki and Toshinao Aoki) published their cartoon versions of amabie on social networks.