There is more to the saya (or Japanese Knife Sheath) than the obvious, well, for me at least.
These obvious benefits of the Japanese saya are important... as well as physically protecting you, your children perhaps and your knife, it also helps to keep the blade dry and away from moisture. This increases the life-span of your knife, along with the sharpness longevity of the edge (especially if they are bashing about loose in a kitchen drawer).
I am also finding however, that the saya can change your perception of the knife itself. After recently adding a saya to all of my home kitchen knives (as opposed to just having my 3 best knives sheathed) I am finding that I am treating them differently, with more care than normal. Having a saya sitting on the bench encourages you to clean and dry your knives straight away... as you should, but maybe do not always do, and has increased my perceived value of each individual knife.
This may not be the case for everyone, but it's been an interesting change. Regardless of your experience, it's a cheap additional that will give your kitchen knife a sharp edge for longer, prevent rust, and decrease the chance of injury.
Our range is still growing, we have some very special walnut saya being crafted in Japan by Hitohira. You can check out the current range here.