-While not abosulute necessary, good command of the Japanese language is a big plus and makes one stand out from non-Japanese speaking Gaijin. It also shows you respect the country enough and are motivated enough that you actually took time to learn Japanese.
-Offer rare skills that are hard to find even among native Japanese. By rare skills, can someone please give a short list about high demand/rare skills.
"While not rare, I can verify that Citrix XenApp Admin/Engineer skills are in demand right now at least in Tokyo." - YokohamaTommy
-Connections, connections, connections. It helps to have connections. It's gets you places, jobs and status.
Things to know
-What's the deal with overtime? Anyone care to elaborate on what's the deal with overtime?
What other stuff shoudl I add?