Here is a quick hint sent in by a Tsukuban who had car trouble today:
My battery died today and I needed a boost. I don’t have any jumper cables in my car, so I thought I would try going to a gas station to see if they could lend me a set. I went to the Eneos just across from Andersen and they were able to lend me the cables for a 2000 yen deposit plus some ID. When I returned the cables, I got my ID and deposit back.
So, if you are ever in the same situation, try to get yourself to the closest gas station to see if you can borrow the cables. Or, if you can’t find a gas station, call your insurance provider to find out if you have road-side assistance as part of your coverage. Finally, if you have 4000 yen to spare, consider joining the Japan Automobile Federation (JAF), so you will always have someone to call when you run into problems like this.