How does the portal in Inuyasha work?

Question

In the Inuyasha series Kagome goes through a portal to get to the Sengoku period of Japan. Is it ever explained how the portal works?

Answer 1

For what I have seen/read, it is never clearly explained how the well actually transports people from the modern age to the Feudal Era. However, the Inuyasha Wikia page on it has a consolidation of observations in regards to who can pass through the well in either direction.

• The only human that is able to travel through the well is Kagome.

• Inuyasha can travel through without any need of the Shikon Jewel; it is mostly because of his connection to Kagome that allows him to move between the two eras of time.

• Neither Sōta nor Shippō are able to pass through the well; however, Sōta's voice could reach Inuyasha for unknown means while Shippō no success what so ever.

• Mistress Centipede was killed and sent to the present era without any need of the jewel; it is suggested that demon's bones can pass through the well. In this case, Mistress Centipede was revived because she was near the Shikon no Tama (which was still in Kagome's body, unbeknownst to her).

• Yura was able to send her hair to wreak havoc in the future; most likely because of the jewel shard she stole.

• Both Sō'unga and Saya were able to pass through without the need of the jewel.

• It can be presumed that only certain beings may pass through the well; a number of objects have the ability to as well.

Kagome is originally pulled through the well/portal into the Feudal Era by Mistress Centipede.

Answer 2

Yes. It was mentioned briefly in a set of episodes. Though it's not consolidated though.

My take on this: Kagome is the reincarnated kikiyo carrying the sacred jewel. The Jewel secretly looks for its admirers which was the demons/humans and others in the Sengoku period. So, the jewel opened the portal for Kagome to come to Sengoku period. As long as the Jewel is there with the user, they can travel back and forth Sengoku and modern period.