Dozen of night trains used to be running in Japan.
The longest one was Hayabusa, which ran between Tokyo and Nishi-Kagoshima(current Kagoshima-chuo). Hayabusa means FALCON in Japanese. Japanese intend to name after limited express from animal or something which are considered as fast.
The era of night train came in 70s when the night trains were called as BLUE TRAIN due to their color of the cars. Definition of BLUE TRAIN were, 1) Limited express 2)Locomotive + carriages of sleepers & couchettes 3)Night train. There were several night trains which were not limited express but express. The most famous and longest existed one was GINGA, which connected Tokyo and Osaka station. Even though GINGA was an electric locomotive with blue couchettes cars, it was not called BLUE TRAIN due to express status.
When the Seikan tunnel opened in the end of 1987, JR East and Hokkaido started to operate Hokutosei, new BLUE TRAIN, connecting Tokyo and Sapporo, prefecture capital of Hokkaido. Hokutosei was the last BLUE TRAIN to appear in Japan but the last operation was in August 2015, which was the last BLUE TRAIN in Japan too.
Sunrise Express debuted in 1998, new concept of night train in Japan. The train has fixed consists(train set) with sleepers and carpet car(no walls between passengers and you sleep on the carpet), no locomotive to pull or push the cars. JR's first night train to abolish couchettes. Then, showers are also equipped.
During BLUE TRAIN era, passengers preferred cheaper way, sleeping on couchettes. However, after air tickets dropped down and long distance buses appeared, JR lost many clients and shifted to high class night trains as like Sunrise Express which led not to consist couchettes.
There are two Sunrise Express. Sunrise Izumo and Sunrise Seto. Izumo connects Tokyo and Izumo-shi, the gateway for Izumo shrine in Shimane prefecture. On the other hand, Seto connects Tokyo and Takamatsu, the major city in Shikoku island. Izumo is popular for female passengers who want to visit Izumo shrine to pray for their marriages and Seto crosses the longest bridge on Earth.
The both trains are connected between Tokyo and Okayama stations. Later Izumo runs on Hakubi line stopping at Bicchu-Takahashi which is close to Bicchu-Matsuyama castle. Seto continues to Seto-Ohashi line toward Shikoku island.
Then, Sunrise Express is convenient for traveler who does not want to overnight in Osaka area but want to be in Tokyo next early morning. Sunrise Express calls at Osaka station at 00:32 and departs at 00:34 and heads Tokyo, therefore you can spend long time in Osaka area or you can take the last Shinkansen from Hakata or Hiroshima and change to local train at Shin-Osaka before getting on at Osaka station. However, watch out that Sunrise Express bound for Izumo-shi/Takamatsu will not call at Osaka station! The first stop after Hamamatsu is Himeji.
For Japan Rail Pass holder, you have to pay both supplements, limited express supplement and fee for sleepers. Carpet car should be without any extra fee.