Do you leave skin on for chashu?

Excuse me, but I'm a bit curious about a culinary practice related to chashu, the popular Japanese pork dish. I've heard differing opinions on whether the skin should be left on or removed before cooking. Can you please clarify for me: Is it customary to leave the skin on for chashu, or is it typically removed? I'm eager to learn the correct way to prepare this dish and ensure I'm adhering to traditional methods. Thank you in advance for your insight.