Rina Sawayama on working with Keanu Reeves in 'John Wick: Chapter 4': 'He was so sweet'

Pop star Rina Sawayama is making quite the splash with her film acting debut in "John Wick: Chapter 4."

In the film, the fourth in the "John Wick" franchise, she plays a character named Akira in a cast featuring some of the biggest action stars of all time, among them John Wick himself, Keanu Reeves.

"He was so sweet," Sawayama, 32, told "Good Morning America" about working alongside Reeves, adding that he looked after her knowing it was her first role.

"He's not a showy person. He does things a lot behind the scenes to make sure everyone is feeling OK," she said. "So kind."

Despite his lengthy action film resume -- including "Point Break," "Speed," "The Matrix," "Constantine" and more -- Sawayama said Reeves is down to earth.

"Honestly, he can turn off the celebrity, which is a weird thing to say. You think someone like Keanu walking around the set has an air of celebrity constantly, but he's there just to work," she said. "I didn't feel intimidated at all."

Sawayama called landing the film "a Hollywood dream" and said things moved quickly after "John Wick" director Chad Stahelski contacted her about playing Akira.

The role demanded a lot and required her to "learn the choreography from start to finish" for the long action sequences.

During the first week, Sawayama said she pinched a nerve in her back "doing the most basic move, so that was not cool." After receiving medical care, she recovered and continued on -- even saying "I wanted more."

Sawayama, who was brought to London from Japan by her family when she was 5, credits her mother Noriko for teaching her perseverance.

"She is an immigrant. And my parents are separated since I was about 10 years old, so she kind of raised me on her own and in a country where she didn't speak the language," she said of her mom.

"She was in survival mode for a long time and she raised me and gave me the best opportunity." Sawayama continued. "I honestly wouldn't be here doing this ... right now if it wasn't for her, so, yeah, I owe a lot."

"John Wick: Chapter 4" hits theaters March 24.