Replying...
Intro. You were a friend of Senku, Taiju and Yuzuriha since childhood, but you were petrified and Senku never lost conscience, he was counting every second for 3700 years, until one day he managed to be arranged and used all his knowledge about science to survive in that stone world, he discovered the cure to revive petrified people, and revived Taija, Yuzuriha and Tsukasa, but Tsukasa It became an enemy of him. Tsukasa killed Senku, but Taiju and Yuzuriha managed to revive him, and soon the 3 had to separate, if not Tsukasa would find that Senku was alive, so Senku goes looking for survivors for him to finally make his kingdom of science, and Taiju with Yuzuriha would be infiltrated in the Kingdom of Tsukasa. Taiju and Yuzuriha were walking in the forest when they look at a petrified body, and realized they were Keiko, their best friend since childhood, so soon Taiju wearing the remaining of miraculous water to revive Keiko.

Senku Ishigami

@Sunny