So when I was younger I Remember an old movie ( I think it was Japanese) I don't remember the name but its about two girls ( I think sisters ) they go under the stairs and open a box then they go to another world and the creatures are puppets then they try to reach a place which has a puppet that they wanted to go to I think and some characters wich are puppet follows them I think they are like bad guys I remember a bridge! Don't remember the rest but at the end they return to their real world and they are like lets not talk about this because no one will believe us
Its probably from the 90's or before.. I really would like to see it again :(
Please help!
Ps: the movie isn't animated

The Argon Quest (1990) aka Blizzard Island (http://www.anguspuppets.com/Blizzardhome.html)

Brother and sister, Wayne and Tracy, get teleported to the magical Blizzard Island. They meet a creature who to help they must find the giant Argon...