Hi David
My first question would always be: what do you want the traffic to provide you? Is it merely for exposure to your work (which looks ace by the way), or do you want it specifically to convert?
If it's just to drive traffic and general awareness of the blog, it frees up the keyword choice. If you want to get people to hire you on a freelance basis, then of course you need to think of the commercial viability of the keyword. For instance, Jiyugaoka Station may not be too commercial, as you're not targeting people looking for a service, whereas "photographers near Jiyugaoka Station" (just as an example) would be. This advice is a bit off topic, but always worth keeping in mind.
The keyword difficulty tool in Moz is a great tool, but I'd combine it with a few other tools. Use the Google Keyword Tool to get a rough idea on monthly search volume for your selected keywords (remember to select [exact] match) and see which keywords have the most search volume - which in turn would probably mean more users to your site should you rank for the term.
The Keyword Tool will also give you a few keyword variations when you enter your keywords - these may also provide some good ideas of other keywords you could target. Similarly, Ubersuggest is a great free tool that does the same sort of thing.
Once you have a list of keywords with decent search volume, then I'd use the Moz difficulty tool. The tool will show you how strong the websites are ranking for that keyword and, somewhat proportionatly, you'll get some idea of how much SEO effort you'd need to do to overtake them. It might be the case that one keyword has a search volume of 800 per month, but looks quite difficult to rank, whereas a 450 per month term looks very easy indeed. In this case, based on your time, knowledge and budget, you can work out which keyword you'd be better off optimising for.
Hope this helps in some way and if you have any interest I wrote a blog post on a relatively similar subject last week: www.sowhatmedia.co.uk/small-traffic-big-business/