Short answers, pulled from the story.
The Morinomiya kaizuka mound contains 2,000-year-old debris from the Jomon and Yayoi periods. Archaeologists found arrow heads, stone tools, fishing hooks, and crockery with remains of rice processing inside these shell mounds.
Osaka merchants organized storehouses where they stored daimyōs rice in exchange for fees trading it for coin or receipts essentially creating paper money precursors. The Rice Exchange established itself at Dōjima in 1697 becoming the world's first futures market selling rice not yet harvested.
Population surpassed three million in the 1960s initiating large-scale suburbanization within the prefecture eventually doubling to six million by the 1990s. The Great Kanto earthquake caused mass migration to Osaka making it Japan's largest city with 2,453,573 people outnumbering Tokyo which had 2,070,913 residents at that time.
On the 13th of March 1945, 329 Boeing B-29 Superfortress heavy bombers participated in air raids against Osaka by United States Army Air Forces. The U.S. bombed the city again twice in June 1945 and once more on August 14 a day before Japan surrendered.
May 2015 referendum approval saw narrow victory of no leading Hashimoto announcement withdrawal from politics. Second referendum merging 24 wards into four semi-autonomous wards narrowly voted down by 692,996 votes representing 50.6%.