The next challenge you will face in constructing a Japanese resume is learning what to include. Here, the basic rule is that you include only full-time employment. But I will ask if I am able to violate that rule to show that I have been teaching English in Japan. This will prove valuable for my employment here.
Other than that, the employment section is not especially challenging to fill out. For the line where you enter a job, you generally write 入社 (entered society -- as reaching employment means you have become a 社会人). When you leave work, you can explain this in a number of different ways:
(1) You can indicate that you "一身上の都合により退社" (i.e. have departed from the above organization [company] due to personal circumstances --> left for personal reasons).
(2) If you don't want to say why you left, then you can just say simply 退社
(3) If you want to explain that it was a downsizing,etc., the following phrases can be useful:
If you go back to the same employer, add a line that says 再入社
For your current place of employ place a line beneath it that says: 現在に至る.
[HT: https://madtokyo.wordpress.com/category/get-a-job-in-japan/rirekisho-the-japanese-resume/ and
for helpful information on this part of the CV]