This original musical instrument of mine is named "one-key string". It is made of a string spanned　on harder timber sandwitched with softer timber from the both side. A piece of the layered timber　jigsawn out from the body is set on the other side as a sound block. In other words, the instrument is on the one side a single-string violin or guitar (however also equipped with a piano-like keyboard in case the player has a difficulty in picking action,) but　also a xylophone on the other. An easy-to-grab screwish fader is provided, too, to enable tuning the instrument, modifying the sound with vibrato, or even with portamento, sliding note like that of a Chinese fiddle. The instrument also fits nicely with percussion using a stick or a mallet. It is robust and safe, with rounded protrusions only (cautions were taken so as to clear the outer surface of metal fittings used for fixing the string etc.) Its shape was conceived for holding it like in a hug to play stably, and is given the small just like human waist toward the lower-pitch part. Though you can play it alone (namely in a single note,) the original concept assumes an ensemble of several players just like a hand-bell choir. Existing types of instruments can also join the concert of course.