Koto is a special kind of musical instrument from Japan that is shaped like a very long and flat wooden box. It has strings stretched over it that you pluck with your fingers or sometimes with picks.
It makes a very beautiful sound that is sometimes soft and gentle like a lullaby, and sometimes fast and exciting like a race car. The koto is usually played by sitting down and placing the long box on the ground in front of you.
The strings on the koto are tuned to different notes, kind of like the keys on a piano. To play a song, you pluck the strings in a certain order and use your other hand to press down on the strings at different points to change the pitch (how high or low the sound is).
It takes a lot of practice and skill to play the koto well, but when you do, it can create very beautiful and peaceful music that can make you feel calm and relaxed.