Seisenryo.

Kiyosumi-ryo, which has been part of Kiyosato's pioneering history, was built in 1938 by Dr Paul Rush, who later founded the Keepers' Association, as a youth guidance and training centre (Kiyosumi-ryo campsite) for the Japanese Brethren of the Andere Brethren, "on condition that the location had a view of Mt Fuji".
It was destroyed by fire in 1955, but was rebuilt in 1957 and the red triangular roof of the main building has been a landmark of Kiyosato ever since.
The X-shaped cross is a symbol of the Japanese Brethren of the Saints, who founded Seisen-Ryo, and the X-shaped cross is a reference to the crucifixion of a sinner on an X-shaped cross, which was used for executions in those days, because the same cross as Christ's was too dreadful. The X-shaped cross is derived from the fact that sinners were martyred by being crucified on the X-shaped cross, which was used for executions in those days.
Various suggestions were made for the name of the Seisenryo campsite, which was completed in 1938 (Showa 13), including naming it after a Bible verse or the name of the surrounding mountains. The suggestion was made that the name "Seisen-ryo" should be taken from the first letter of both place names,
When Dr. Kikuchi heard that the English translation of the name was "Pure Spring" (Seisenryo campsite with a clear spring), he was delighted and agreed with the naming.
Today, it is a major amusement park offering accommodation, food and drink, souvenirs and tours.