Uro

The Uro are mushi who are usually found in closed spaces. They are capable of opening portals into our world. They travel through the Uro passageway.

When the Uro are young they usually occupy empty double cocoons. The double cocoon can be split into two seperate cocoons and can be used to restrict the uro's movements. This can be used to pass on letters, this can be done if the person to whom the letter is destined to has one of the two cocoons. One can simply insert the letter into one of the cocoons, and the person with the other cocoon recieves the letter throught the uro.

However, the cocoons have to replaced after a few years as the uro rapidly expand the uro passageway after leaving their cocoons and penetrate into another passageway when this starts happening the letters dont get delivered properly.

If an area where the uro are commonly found, then in that area one must never close the doors completely, and if someone does accidently close the door completely then they must never open it as the Uro inside will try to escape and suck the person along with it to the uro passageway.

Weakness:

They cant live long outside a closed space.