Miyazaki Toten was a Meiji-era would-be revolutionary whose dreams of a Chinese restoration led him to become the right-hand man of Sun Yat-Sen, traveling throughout Asia to make connections and agitate for a Chinese uprising against the Qing Dynasty and Western colonial powers. This autobiography served to introduce Sun and his ideas to the Japanese reading public, though the book was written in 1902 when things didn't look so good for revolutionaries in China, and Miyazaki wrote it as if his life's work had been a failure. In fact, he gave up his pan-Asian scheming and became a performer of naniwa-bushi, a type of ballad singing, for a time. He was back with Sun by the time of the 1911 Xinhai Revolution, although that's not covered in the book.
Though Japan was in the early stages of becoming an empire during this time, Miyazaki's hopes for Asia and the schemes they lead him to are distinctly in line with Sun's pan-Asianism rather than Japan's nascent colonialism.