On her very first Saturday night in the city last March, at a clandestine Japanese lounge operating without a liquor license in Midtown, Ms. Mimura ordered a drink more appropriate to the girl she still was than the woman she aspired to be: milk and Malibu rum. She had arranged to meet a fellow student from her first hip-hop class who went by the nickname Smiles, and a friend of his. Before their arrival, Ms. Mimura confided, “I want American boyfriend.”

She spent those first weeks struggling to learn her way around the city. She found it difficult to navigate the subway or to find Internet access. For a month, she slept on the couch in the Brooklyn apartment of her best friend from childhood, a design student at LaGuardia Community College. The two women spent hours in deep conversation.

Ms. Mimura wrote in her diary about her ex-boyfriend and why he had abandoned her. In one entry, which she allowed a reporter to read with the help of a translator, she confided that she had been needy and insecure around the boyfriend. Six months after the breakup, it was still hard to let go. She phoned him from New York and they talked about why their romance had ended. “I still need him,” Ms. Mimura said.

One night, Ms. Mimura went to the East Village club Sin Sin, at a monthly party called “Soulgasm,” where a well-known dancer, Henry Link of Elite Force Crew (who has danced for Michael Jackson and Mariah Carey), often shows up. The party is popular with young Japanese women interested in hip-hop culture.

About 1 a.m. Mr. Link appeared, dressed in a T-shirt and track pants, and soon a circle formed around him as he danced. From time to time challengers stepped into the circle to battle, using their own dance moves, with crowd reaction measuring their success.

Ms. Mimura bounced with anticipation. In Japan, she never would have tried such a thing, but when an opening came she handed her beer to a bystander and plunged into the circle. Mr. Link stood back in admiration, and spectators nodded and clapped.