Question

How did Japanese social structure change during the Tokugawa period?

Answer 1

Virtually no big war in one stable government for over 250 years. 

As commerce flourished and the merchant class gradually gained economic power during these peaceful years, a new urban culture developed and it became very sophisticated. 
The literacy rate in Edo was estimated about 70-80%, whereas Paris was about 10%, London was about 20%, in 18th. Century. Infrastructures, like Sewerage system, were well organized and the streets were kept clean. 
The capital of commerce, Edo, had became the biggest city in the word. 

On the other hand, citizens became very obedience to the government and democracy had not be developed.