Endeavor is an electronic ensemble from Hong Kong, made up of radio host Alvin Wong and his two friends. Their music has a strong flavor of baroque / continental European folk music, while the titles are often low-key references to the 1989 Tiananmen Square incident. I'm not sure how this piece "Book of Rainy Days" relates to the 1931 anthology of the same name by Zhou Zuoren, but musically it sounds like baroque organ music.