The "Whyman" is the name Ryusui gives to the source of powerful radio wave messages the Kingdom of Science receives after the creation of antennae. The name is chosen as the messages consist only the word "why" in Morse code.
The true nature of the Whyman is unknown. Some in the Kingdom of Science speculate the source is a group of survivors of the Petrification. Others, including Senku, believe they could be the ones responsible for the Petrification.
Determining the nature of the Whyman is a major goal of the Source of the Petrification Saga.