Churenji Temple is one of the stranger and more serious temple visits in the Tsuruoka area. It is associated with Kukai, but its best-known feature is the preserved body of Tetsumonkai, a monk who became one of the region's sokushinbutsu, or self-mummified ascetics.
The temple sits outside the city, so it is not a casual drop-in between central sights. Go if you are already exploring the Dewa Sanzan side of Tsuruoka and want to understand the austere religious traditions that shaped this part of Yamagata.