This is a Hello Kitty version of the Korg AW-2G, a classic clip-on tuner that was only released for a limited time. There are two versions of Kitty-chan, white and black, and this one is black. Currently, it's being traded on Amazon for 20,000 yen used. I've only used it to confirm it works. It's sold primarily for use with ukuleles, guitars, and basses, but I think it can be used with other instruments as long as you're just using it for tuning. I liked it so much that I bought a spare of the same model, but it's durable and long-lasting, so I'm selling the extra one.