Kōkoku-ji houses a futuristic octagonal columbarium called Ruriden with 2,046 digitized crystal Buddhas that light up via smart card when visitors come to honor their deceased loved ones.

Two ancient ginkgo trees at Kōkoku-ji, estimated to be over 300 years old, survived both the Great Kanto Earthquake of 1923 and the devastating air raids of 1945.

The temple's columbarium stores cremated remains for exactly 33 years before burial, reflecting the traditional Buddhist belief that the deceased's spirit completes its journey in that timeframe.

Each of the ancient ginkgo trees wears a small plaque around its thick, gnarled trunk proudly proclaiming its estimated age of three centuries.