what mountain range runs through Japan

You're probably thinking of the japanese alps. I've sailed past the coast there a few times and they honestly look pretty massive from the deck, especially when you catch them in the early morning light. They basically cut right through the center of the main island, honshu, and they're definitely the most famous range you'll hear about.

There's also a bunch of smaller ranges scattered around, but the japanese alps are the ones that really dominate the landscape. If you're ever planning a trip or just looking at maps, you'll see why they call it a mountainous country. It's pretty wild how much elevation change there is once you move inland from the ports.