Passageways? Plural? Spirit worlds? Again, plural? Are you kidding me?

No... this world is more complex and stranger than you can imagine.

Starting with spirit worlds, shintô has at least three, and the Buddhists have multiple paradises, plus a truly excessive number of hells — as many as 10 million according to some sects. Apparently Buddhists are much more inventive when it comes to "sinning".

As for how does one get there, there are several "portals".

The most common is to enter either thru water or mirrors — the reversed image is seen as a different world.

One could get hopelessly lost in a wild forest, or climb a sacred mountain. There are plenty of spirits who will cheerfully mislead you for trepass.

Dusk and dawn are good times for entering a spirit word — these are liminal times where reality is blurred.

For the brave of heart you could try fire, but expect to arrive slightly singed.

Of course, there's always walking shrine pathways. Not all will reliably get you back to the shrine.

Frankly you're not even safe at home. There are several actions that can bring you to the notice of spirits. (see superstitions)