This is the flashlight that was found; it was found in a box with post cards and other documents about his ship, so we assume that is from the war. The outer case of the flashlight is made of wood and it had two large batteries (sitting on either side of the flashlight) with Japanese writing. I'm sorry I don't have any other photos, I wasn't there with them when they found it, but hopefully I can get back to their house soon to get a better picture or two, I came here to see if maybe someone can shed a little light on what we have found (no pun intended)
That's a neat photo. This appears to be one of the flashlights Panasonic was marketing during the war under the brand name National. It's likely made of wood because metal was needed for the war effort. Here's a photo of a similar wooden flashlight from the Panasonic Museum in Tokyo. Perhaps others will have more on this, but that's the best I can do.