Can you help me figure out the title of this animated series from the 80s?

Been wracking my brain for almost an hour now and so naturally, I go to Fluther for the answer so I don’t end up jumping off a cliff. LOL

I only have vague memories of it. I think it’s Japan produced but not certain. The main character, a boy, owns a small cute doll, a teddy-bear like toy character that holds a hammer.

In every episode, in order for them to get back in their own world, the teddy-bear toy has to strike the hammer down to open a portal. The teddy-bear is alive when they’re on an adventure in another dimension but in the real world, he is just an ordinary toy.

That’s all I can remember.