The "Whyman" is the name Ryusui gives to the source of powerful radio wave messages the Kingdom of Science receives after the creation of the antennae. The name is chosen as the messages consist only of the word "why" in Morse code.
The "Whyman" is the main antagonist of Dr. Stone.
The face and gender of Whyman is unknown.
The true nature of the Whyman is currently unknown.
For unknown reasons, Whyman attempted to petrify humanity again with attempted usage of petrification device.
Age of Exploration Arc
The Whyman is first heard communicating with the Kingdom of Science using Morse code on the motorboat. The message consisted of one word, repeated over and over: “Why?".
Determining the nature of the Whyman is a major goal of the Source of the Petrification Saga.
Treasure Island Arc
After the conflict on Treasure Island is done, a signal takes over the radio in an attempt to activate the petrification device, with the distance being Earth's diameter and the time 1 second. This call has the Kingdom of Science confirm that Whyman is a villain. However, the voice, as noted by Ukyo is the same voice as Senku.
New America City Arc
The source of the Whyman's transmissions is apparently on the Moon.
The Kingdom of Science decides to travel the world and gather supplies for space travel to confront the Whyman. Some members want answers while others, like Matsukaze, want revenge.