Yoshiko made her debut as an actress and singer in the 1938 film,
Honeymoon Express (), by
Manchuria Film Production. She was billed as Li Hsiang-lan, pronounced Ri Kōran in Japanese. The adoption of a Chinese stage name was prompted by the film company's economic and political motives – a Manchurian girl who had command over both the Japanese and Chinese languages was sought after. From this she rose to be a star and the
Japan-Manchuria Goodwill Ambassadress (). The head of the Manchukuo film industry, General
Masahiko Amakasu, decided she was the star he was looking for: a beautiful actress fluent in both Mandarin and Japanese, who could pass as Chinese and who had an excellent singing voice. The Chinese actors who appeared in the Manchuria Film Production movies were never informed that she was Japanese, but they suspected she was at least half-Japanese as she always ate her meals with the Japanese actors instead of the Chinese actors, was given white rice to eat instead of the sorghum given to the Chinese, and was paid ten times more than the Chinese actors were. Though in her subsequent films she was almost exclusively billed as Li Hsiang-lan, she appeared in a few as "Yamaguchi Yoshiko". Many of her films bore some degree of promotion of the Japanese national policy (in particular, pertaining to the
Greater East Asia Co-prosperity Sphere ideology) and can be termed "National Policy Films" (). While promoting Manchurian interests in Tokyo, Li would meet
Kenichiro Matsuoka, future television executive and son of Japanese diplomat
Yōsuke Matsuoka, about whom she would write in her biography,
Ri Kōran: My Half Life, to be her first love. Although she had hopes of marriage, he was still a student at
Tokyo Imperial University and not interested in settling down at the time. They would meet again after the war, at which time Kenichiro attempted to rekindle the relationship, but by then, Li was already involved with the artist
Isamu Noguchi. The 1940 film,
China Nights (), also known as
Shanghai Nights (), by Manchuria Film Productions, is especially controversial. It is unclear whether it was a "National Policy Film" as it portrays Japanese soldiers in both a positive and negative light. Here, Li played a young woman of extreme anti-Japanese sentiment who falls in love with a Japanese man. A key turning point in the film has the young Chinese woman being slapped by the Japanese man, but instead of hatred, she reacts with gratitude. The film was met with great aversion among the Chinese audience as they believed that the Chinese female character was a sketch of
debasement and inferiority. 23,000 Chinese people paid to see the film in 1943. After the war, one of her classic songs, "" (), was banned in China due to its association with this film. A few years later, when confronted by angry Chinese reporters in Shanghai, Li apologized and cited as pretext her inexperienced youth at the time of filmmaking, choosing not to reveal her Japanese identity. Though her Japanese nationality was never divulged in the Chinese media until after the Sino-Japanese War, it was brought to light by the Japanese press when she performed in Japan under her assumed Chinese name and as the Japan-Manchuria Goodwill Ambassadress. When she visited Japan during this period, she was criticized for being too Chinese in dress and in language. When she landed in Japan in 1941 for a publicity tour, dressed in a
qipao and speaking Japanese with a Mandarin accent, the customs officer asked her upon seeing she had a Japanese passport and a Japanese name, "Don't you know that we Japanese are the superior people? Aren't you ashamed to be wearing third-rate
chankoro clothes and speaking their language as you do?" In 1943, Li appeared in the film
Eternity. The film was shot in Shanghai, commemorating the centennial of the
Opium War. The film, anti-British in nature and a collaboration between Chinese and Japanese film companies, was a hit, and Li became a national sensation. Her film songs with
jazz and
pop-like arrangements, such as her "Candy-Peddling Song" () and "Quitting (Opium) Song" (), elevated her status to among the top singers in all Chinese-speaking regions in Asia overnight. Many songs recorded by Li during her Shanghai period became classics in Chinese popular music history. Other noteworthy hits include "Evening Primrose / Fragrance of the Night" (), "Ocean Bird" (), "If Only" (), and "Second Dream" (). By the 1940s, she had become one of the
Seven Great Singing Stars. ==United States, Canada, Hong Kong, and Japan==