Top 4 in Top 10 smartest characters in anime Dr.Stone.
Ryusui Nanami is one of the 5 generals of the Kingdom of Science because of his special skills and talents. Although introduced late in Dr.Stone, Ryusui Nanami is undeniably an intelligent person.
Unlike any of the characters in Dr Stone, Ryusui Nanami comes from a wealthy family. Ryusui knows a lot of things, especially when it comes to ships. So Senku decided he became the Captain. Ryusui is not as smart as Senku, but Ryusui's existence in the Kingdom of Science makes things much easier.