If you continue on past the Shinden you will come across a room with a high ceiling which is called the rainbow room or “Niji-no-Ma”.
Past Niji-no-Ma and you will find a room on a raised platform. This is the “throne room”. This room was installed so that the emperor could come at any time he pleased. One thing we would like to point out is that the throne room is sitting 10 cm higher than the room we are currently standing in.
On the wall to the right leading up to the throne room, did you notice against the white of the wall there are small water plants drawn against the surface? Once you have found these, turn and look at the sliding screen on the other side. There, very faintly, a rainbow is painted. The water plants spread between this room and the next. the rainbow reaching across the white wall, and the tatami beneath your feet, which represents the surface of a pond.
The rainbow is actually tied to the power and authority of the royal family. The imperial family and its members are said to be direct descendants of the sun goddess, Amaterasu Ōmikami. Thus, the temples where descendants of the emperors live also flows with the blood of the goddess as well. Makes sense, right?
After examining the rainbow sliding screen, we will move on to the highlights of Sanzen-in: Yūsei-en and Ōjō Goraku-in.