I got good information from my friend. We can see inside the bulding of the Geihin-kan now.
The Geihin-kan (State Guest House) is a facility in which the government accommodates visiting state guests, such as heads of state or ministers.
Cabinet Office ,Government of Japan announced that, "Based on the outcome of the trial opening of a limited period in February, public opening throughout a year avoiding the periods of the visit of foreign dignitaries commences this April." more info click here
I got off at Yotsuya Station at 8:45 and ran to the Geihinkan entrance. And I was able to get an admission card.
After going through the security check , I paid 1000yen for addmission fee. I really enjoyed to see them because I borrowed a rental guide instrument.
There were some prohibited acts , No photography and don't touch thｅ walls.
Big wonderful chandeliers , marble columns and pictures were imported from France. It's called Versailles palace of Japan. The pictures of cloisonne which were made in Japan gave an impression on me deeply.
I felt as if I were in a foreign country. because it was clean and blue sky.