Answer by taking a quote from the following article:

Utada Hikaru (Yu Duo Tian hikaru, born January 19, 1983), who also goes by the mononym Utada (English: ), is a Japanese-American singer-songwriter and producer. Born in New York City to Japanese parents, record producer Utada Teruzane and enka singer Abe Junko, Utada began to write music and lyrics at an early age and often traveled to Tokyo, as a result of her father's job. Eventually, a recording contract with Toshiba-EMI was signed and, under the stage name "Cubic U", Utada released her English-language debut album Precious in early 1998, but was a commercial failure. In the following year, heavily influenced by R&B and dance-pop, her Japanese-language debut First Love was released and became an instant success.

On December 16, 2008, information leaked onto the Internet that Utada's next English-language single, titled "Come Back to Me", would be scheduled for airplay release through U.S. Rhythmic/Crossover and Mainstream formats on February 9 and 10, 2009 respectively via Island Records. The new English album, titled This Is the One, was released on March 14, 2009 in Japan and on May 12, 2009 in the United States. This Is the One debuted at number 1 in Japan on March 13, 2009, the day it was released in Japan, but became Utada's first album not to top the weekly chart since Precious. On March 30, 2009 she appeared on New York City radio station Z-100 (100.3), the largest pop radio program in the U.S., and granted a live on-air interview on the station's Elvis Duran Morning Show, a breakthrough that would lead to a promotional schedule up and through the album's international physical release on May 12. Utada also sang the theme song for the second Evangelion film, Evangelion: 2.0 You Can (Not) Advance. The single was released on June 27, 2009, and is a remix of her previous single, "Beautiful World". The new single is titled Beautiful World -PLANiTb Acoustica Mix-. On October 14, Utada stated that she was writing lyrics that were due on October 15. She also added that some "German magic" would be added to the music. It was revealed that Goetz B, who had previously worked with Utada on her album Ultra Blue was in the process of mixing tracks for her. On November 30, 2009, at Studio Coast, Tokyo, Utada sung a duet of Let It Snow with pop singer Mika. On December 21, 2009, Utada's Dirty Desire remixes were released only on Amazon.com, Zune Marketplace, and the U.S. iTunes Store, in support of This Is the One and her upcoming tour. The tour, Utada: In the Flesh 2010, was her first concert tour outside Japan and included eight cities in the US and two dates in London, UK. The tickets for the second London performance went on public sale November 13, and reportedly sold out in just 5 hours.

Did she do anything else during this time?
On October 14, Utada stated that she was writing lyrics that were due on October 15.