This is the CORE DRIVE by PSK. Operation confirmed. I think it's become rare on the market recently. This is the vintage high-gain distortion "Core Drive CDV-5" by the Korean brand PSK. It's a valuable effector that is now discontinued, and is known to have been used by tetsuya of L'Arc〜en〜Ciel. It features a thick and powerful sound with distortion, and is recommended for rock and metal guitarists.