Piperine, along with its isomer chavicine, is the alkaloid responsible for the pungency of black pepper and long pepper. It has been used in some forms of traditional medicine.
In the Japanese constitutional monarchy, the emperor does not have any political power. In world politics, he is the only current emperor. The current emperor is His Imperial Majesty the Emperor Akihito. He has been on the Chrysanthemum Throne since his father Emperor ShÅwa (Hirohito) died in 1989. The amount of power belonging to the emperor of Japan has changed a lot throughout Japanese history.
Perhaps you mean what dynasty reigns in Japan. Akihito is the reigning Emperor of Japan, the 125th emperor of his line according to Japan's traditional order of succession. He acceded to the Chrysanthemum Throne in 1989. If you read wikipedia, you will observe a more balanced view of China's dynasty. Currently, and namely, there are 2 dynasties in China, with PRC being the de-facto ruling dynasty, with another less powerful ROC dynasty.