Toyotomi Hideyoshi is the extreme example of climbing the social ladder. Hideyoshi was born as peasent.
Throughout the years, Hideyoshi grew in power, from peasent, to samurai, to general, and when Oda Nobunaga
was assasinated, Hideyoshi hunted down the assasin with his army, and killed him and his men. After that, he
claimed the domains that were previously Oda Nobunaga's. Many poeple agreed, after all, he did avenge Nobunaga.
After that, he continued untill all of Japan was under his rule. He even attempted to invade Korea (which failed
because of weather contitions and naval ambushes). After that he died of old age, and his son was not old enough
to run the country, so he left generals incharge.