If you are looking for a fast flat course, Osaka marathon is that course. It goes through the major city of Osaka, and there is crowd support from the beginning of the race until the end. At no point is there a section that doesn't have someone cheering for you. There is a slight hill at mile 23, but this is the only hill on the course. I expo is decent with lots of vendors, and the t shirt and medal is amazing. Since this marathon has the option for running for charity, you have the option of getting another shirt and hat which are decent looking. The race is sponsored by mizuno.