Princess was a Japanese socialite in the Meiji era, and the first Japanese woman to receive a college degree. She was born into a traditional samurai household which supported the Tokugawa shogunate during the Boshin War. As a child, she survived the monthlong siege known as the Battle of Aizu in 1868, and lived briefly as a refugee.

In 1871, Yamakawa was one of five girls chosen to accompany the Iwakura Mission to America and spend ten years receiving an American education. At this time, her name was changed to , or, when she wrote in English, Stematz Yamakawa. Yamakawa lived in the household of Leonard Bacon in New Haven, Connecticut, becoming particularly close with his youngest daughter Alice Mabel Bacon. She learned English and graduated from Hillhouse High School, then attended Vassar College, the first nonwhite student at that fledgling women's university. She graduated with the Vassar College class of 1882, earning an A.B. After graduation, she remained a few more months to study nursing, and finally returned to Japan in October 1882.

When she first returned to Japan, Yamakawa looked for educational or government work, but her options were limited, especially because she could not read or write Japanese. In April 1882, she accepted a marriage proposal from Ōyama Iwao, a wealthy and important general, despite the fact that he had fought on the opposing side of the Battle of Aizu. As her husband was promoted, she was elevated in rank to become Countess, Marchioness, and finally Princess Ōyama in 1905. She was a prominent figure in Rokumeikan society, advising the Empress on Western customs. She also used her social position as a philanthropist to advocate for women's education and volunteer nursing. She assisted in the founding of the Peeresses' School for high-ranking ladies, and the Women's Home School of English, which would later become Tsuda University. She died in 1919 when the 1918 flu pandemic reached Tokyo.

Early life Yamakawa Sakiko was born on February 24, 1860, in Aizu, an isolated and mountainous region in what is now the Fukushima Prefecture. Her father, , was a karō (senior retainer) of Hoshina family who ruled the Aizu domain, and her mother Tōi came from another karō family, the . Yamakawa was the youngest child, born a few months after her father's death; she was raised in her grandfather Shigefusa's household. Of her parents' twelve children, seven survived. Yamakawa had three sisters, , Misao, and Tokiwa; and two brothers, and .

Yamakawa was raised in a traditional samurai household in the town of Wakamatsu, in a several-acre compound near the northern gate of Tsuruga Castle. She did not attend school, but was taught to read and write at home, as part of a rigorous education in etiquette and obedience based on the eighteenth-century neo-Confucian text Onna Daigaku (Greater Learning for Women). Aizu was known for its emphasis on both education and a strict code of conduct.

Battle of Aizu In 1868–1869, Yamakawa's family was on the losing side of the Boshin War. The Boshin War was a civil war at the end of Japan's bakumatsu ("end of military government"), in which pro-shogunate forces resisted the new imperial rule that began with the 1867 Meiji Restoration. The conflict reached Yamakawa's hometown with the Battle of Aizu in late 1868. On October 8, 1868, when Yamakawa was eight, imperial forces invaded and burned her hometown of Wakamatsu. Yamakawa took shelter within the walls of Tsuruga Castle with her mother and sisters. Several hundred people from other samurai families instead committed ritual suicide, in what would become a famous instance of mass suicide. This invasion marked the beginning of a Month-long siege, which came to be a symbol of "heroic and desperate resistance". It was during the Battle of Aizu that the Byakkotai (White Tiger Brigade), a group of teenage fighters, famously committed mass suicide under the mistaken belief that the castle had fallen.

The 600 women and children inside the castle, led by Matsudaira Teru, formed workgroups to cook, clean, and make gun cartridges, as well as nursing nearly 1,500 wounded soldiers. One of Yamakawa's sisters attempted to join Nakano Takeko's , but on her mother's orders remained inside the castle making gun cartridges. Yamakawa herself, too young for other tasks, carried supplies for the cartridge makers. During the last month of the siege, the castle was bombarded by imperial cannons. A shell exploded in the room where Yamakawa and her family were eating dinner, wounding Yamakawa's neck with shrapnel, and killing her sister-in-law Toseko. In the final days of the siege, Yamakawa's mother sent her and other girls to fly kites as a gesture of defiance while imperial cannons bombarded the castle and the women smothered the shells with wet quilts.

After the battle

The siege ended with the castle's surrender on November 7, 1868. Yamakawa was taken to a nearby prisoner camp with her mother and sisters, where they were held for a year. In the spring of 1870, they were exiled to the newly created Tonami District (an area that is now part of the Toyama Prefecture). The 17,000 refugees exiled there had no experience of farming, and the winter saw shortages of food, shelter, and firewood which threatened Yamakawa's family with starvation. Yamakawa, turning eleven, spread night soil on the fields and scavenged for shellfish.

In the spring of 1871, Yamakawa was sent to Hakodate, without her family, where she was lodged with and then with French missionaries.

Education in America Departure with the Iwakura Mission

In December 1871, when she was eleven years old, Yamakawa was sent to the United States for study, as part of the Iwakura Mission. Yamakawa was one of five girls sent to spend ten years studying Western ways for the benefit of Japan, after which she was to return and pass on her knowledge to other Japanese women and to her children, in accordance with the Meiji philosophy of "Good Wife, Wise Mother". The other girls were Yoshimasu Ryo (age 14), Ueda Tei (14), Nagai Shige (10) and Tsuda Ume (6). All five girls were from samurai families on the losing side of the Boshin War. The initiative was a "pet project" of Kiyotaka Kuroda, who initially received no applicants in response to his recruitment efforts, despite the funding offered: all the girls' living expenses would be paid for the decade, plus a generous stipend. In response to Kuroda's second call for girls to be educated in America, Yamakawa's eldest brother Hiroshi, acting as head of the household, nominated her. Hiroshi was familiar with Kuroda, since his and Yamakawa's brother Kenjiro had recently left for his own education in America in January 1871, with Kuroda's assistance. Hiroshi may have nominated his sister due to her independent spirit and academic strengths, or out of simple financial need. The five girls chosen were the only applicants.

At this time, Yamakawa's mother changed her given name from ("little blossom") to . The meaning of the new name could indicate disappointment that Yamakawa was being sent away from Japan, with the first character meaning , as if Yamakawa had been thrown away. But the name could also indicate a positive hope: is one of the Three Friends of Winter which flourish even in harsh conditions, and it sounds like , suggesting that her mother her youngest daughter to the government mission while awaiting her safe return.

Before leaving Japan, Yamakawa and the others were the first samurai-class girls to be granted an audience with the Empress Haruko, on November 9, 1871. They departed with the rest of the Iwakura Mission on December 23, 1871, aboard the steamship America, chaperoned by Elida DeLong (wife of the American diplomat Charles E. DeLong), who spoke no Japanese. After a stormy and difficult journey, they arrived in San Francisco on January 15, 1872. Yamakawa and the other girls spent two weeks in San Francisco, largely solitary in their hotel room but the subjects of intense newspaper coverage. Americans typically spelled her name as Stemats Yamagawa, and referred to her and the other girls as "Japanese princesses". After two weeks in San Francisco, the Iwakura Mission embarked on a monthlong cross-country train tour, arriving in Washington, DC on February 29, where Charles Lanman (secretary to Arinori Mori) took custody of the girls. Yamakawa lived briefly with Mrs. Lanman's sister, a Mrs. Hepburn, then in May 1872 all five girls were moved to their own house with a governess, to study English and piano.

By October the girls had separated: Yoshimasu and Ueda returned to Japan, Tsuda moved in with the Lanmans, and on October 31, 1872, Nagai and Yamakawa were moved to New Haven, Connecticut. In New Haven, Yamakawa's elder brother Kenjirō was studying at Yale University. To ensure that Nagai and Yamakawa practiced their English, they were placed in separate households, Nagai living with the minister John S. C. Abbott and Yamakawa living with the minister Leonard Bacon. Yamakawa would spend the next ten years as part of the Bacon family, growing particularly close with his youngest daughter of fourteen children, Alice Mabel Bacon. Likely due to the Bacons' influence, Yamakawa converted to Christianity.

Yamakawa attended Grove Hall Seminary, a primary school for girls, with Alice Bacon. In 1875, Yamakawa passed the entrance exam for Hillhouse High School, a prestigious public school, and began her studies there. She attended the 1876 Centennial Exposition in Philadelphia with both Nagai and Tsuda, a rare reunion. In April 1877, Yamakawa graduated from Hillhouse High School.

Vassar Yamakawa began her studies at Vassar College in September 1878, the fourteenth year of the still-new women's college. To her regret, the Bacons couldn't afford to send Alice to college, but at Vassar Yamakawa was reunited with Nagai. The two of them were the first nonwhite students at the school, and the first Japanese women to enroll in any college. Nagai enrolled as a special student in the music department, while Yamakawa pursued a full four-year bachelor's degree.

While at school, Yamakawa began styling her name as Stematz Yamakawa, using the American name order and a spelling which matched the pronunciation of her name. Her teachers included Henry Van Ingen. While she knew Maria Mitchell she did not have her as a teacher. During her time at Vassar, she studied Latin, German, Greek, math, natural history, composition, literature, drawing, chemistry, geology, history, and philosophy. She also mastered chess and whist. Yamakawa was a reserved and ambitious student, whose marks were among the highest in the class. She was also well-liked by her classmates. Around this time, Yamakawa's sister Misao moved from Japan to Russia; Misao wrote letters in French to Yamakawa, which Yamakawa's classmates translated and helped her reply to. Yamakawa was elected class president for 1879, and invited to join the literary club of the Shakespeare Society, which was "reserved for students of formidable intellect." In 1880, she was a marshal for the college's Founder's Day celebration. In June 1881, Nagai returned to Japan. The ten-year period of the girls' educational mission had ended, but Yamakawa extended her stay to complete her degree. In her senior year, she was named president of the Philalethean Society, the largest social organization at Vassar. Whilst at Vassar she also became friends with actress and novelist Louise Jordan Miln who visited her in Tokyo on her travels to the Far East in the 1890s.