The origin of Zhongshan Qiao's pen name

1896 In September, Japanese youth Miyazaki Hayao Heping Mountain saw it in the apartment of a revolutionary in Yokohama, Japan after many twists and turns. When Sun Wen talks about revolution, he is impassioned, like a roaring tiger in the mountains. Deeply moved by Sun Wen's revolutionary enthusiasm, knowledge and ambition, they were determined to help Sun Wen and worried about his life safety, and advised him to stay in Japan for the time being. After Sun Wen agreed, Miyazaki Heping Mountain accompanied Sun Wen to find a hotel. They bypassed Hibiya Park, passed Houjue House in Zhongshan, and came to the "Duihe Pavilion" hotel where Sun Wen was registered in Pingshan. At that time, Sun Wen was in exile, so it was not convenient to disclose his name and identity. What should I fill in? Hirayama hesitated for a moment, suddenly remembering the plaque he saw when he walked past the Marquis House in Zhongshan, so he wrote the word "Zhongshan" in the hotel book. However, according to Japanese custom, Zhongshan is just a surname, so it needs a proper name. Hirayama hesitated again. Just then, Sun Wen took the register, added a word "Chai" under the word "Zhongshan" and said to Pingshan with a smile: "I am Shan Chai from China." This is the origin of Sun Yat-sen's name.