Board Thread:Questions and Answers/@comment-30535075-20180216171039/@comment-26912075-20180324185838

Well, Ichigo was able to fly downward from the royal palace to ss and has never shown the ability to dimensionally travel, so they must be in the same plane of existence. I think Unohana was exaggerating there, as there has never been a sign that Muken was in a separate realm, especially when Yhwach was able to get there by foot and Yamamoto stated that they were under the first court guard squad barracks.