Paintings play a fundamental role in the series, and serve as a mutual connection between Earth and purgatory.
Through a process called "linking", ghosts from purgatory can use paintings to travel from one dimension to another by simply phasing through them. This ability is limited only to ghosts in purgatory, but there is at least one exception. There is an extensive gallery in purgatory housing numberless paintings separated by continent, country and city, for ease of access. A few of them hang in Kleinod and Weltraum's dorm for them to get to certain places faster.