Masami Nagasawa is a prominent Japanese actress who began her career in live-action film and television before expanding into voice acting. She was born on June 3, 1987, in Iwata, Japan. Her entry into the entertainment industry came at the age of twelve when she won the Grand Prix at the fifth Toho Cinderella Audition in 2000, a competition that launched her career in Toho films. She is primarily known as a live-action actress, having received numerous accolades including Japan Academy Prizes, Blue Ribbon Awards, and a Mainichi Film Award.

Nagasawa's foray into voice acting began in 2011 when she was cast as the lead character Umi Matsuzaki in the Studio Ghibli animated film From Up on Poppy Hill, directed by Gorō Miyazaki. This role marked her official expansion into anime voice work. Prior to this, she had provided narration for the animated short La Maison en Petits Cubes in 2008 and voiced the character Yuri Aikawa in the television series adaptation of Detroit Metal City, also in 2008. Her most internationally recognized voice role came in 2016 when she voiced Miki Okudera in Makoto Shinkai's critically acclaimed and box office hit Your Name. She has also contributed her voice to other animated projects, such as the character Fiona in the 2018 film Doraemon the Movie: Nobita's Treasure Island.

Her body of voice work, while not as extensive as her live-action filmography, includes collaborations with prestigious directors and studios. Through her role in From Up on Poppy Hill, she worked with Studio Ghibli, and with Your Name, she collaborated with the renowned director Makoto Shinkai. Information regarding recurring collaborations specifically within the anime voice acting industry is not documented in available sources. Nagasawa's achievements are predominantly in live-action, but her involvement in major anime productions like From Up on Poppy Hill and Your Name has made her a familiar voice to anime audiences worldwide. Her voice performance in Your Name contributed to the film's international success.