SINGAPORE - Over the past nine years, Japanese actor Kento Yamazaki has carved a career out of playing high-schoolers in youth-centric films such as teen romance movie Wolf Girl And Black Prince (2016).

The 24-year-old has also had starring turns on the small screen, including playing the lead role in the 2018 Japanese remake of the South Korea hit drama series Good Doctor and taking on the role of detective L in crime fantasy thriller Death Note (2015).

For a change of pace, he heads to the past to headline the historical action film Kingdom, which opens here on June 20.

It is set in the Qin Dynasty during the warring states period in ancient China and features Yamazaki as orphan Shin, who aspires to become the greatest war general ever.

Yamazaki, who was in town on Monday (May 27) for a press conference at Marina Bay Sands, said in Japanese through a translator: "Shin is very pure-minded and his dream is just to be the greatest under heaven. I felt that I want to be like him and I want to live like him." He was dressed in an unstructured grey suit over a black T-shirt.

Shin meets the rightful heir to the Qin Dynasty throne, Ei Sei, played by 25-year-old Ryo Yoshizawa (Marmalade Boy, 2018), and they set out on a quest to reclaim it.

Kingdom is based on Japanese writer Yasuhisa Hara's popular manga series of the same name, which has sold more than 40 million paperback volumes since the series started in 2006.

Yamazaki was a fan of the series before he was cast in the movie and landing the role was an exciting moment for him. At the same time, filming was no walk in the park.

He said: "Shin is a self-taught warrior so his style of fighting is unique. I had a lot of difficulties acting this role because Shin's style of fighting changes depending on the enemy."

But there were also light-hearted moments on the set.

Yamazaki and co-star Yoshizawa are good friends off-screen and it was sometimes hard to keep a straight face while acting opposite each other in serious scenes, such as when they had to film a sword-fight training scene.

"We were acting with very serious expressions but the wooden sword slipped... we collapsed laughing when the director said 'cut'."

The movie has already proven to be a hit in Japan, where it debuted in mid-April and has since grossed more than US$41 million (S$56.5 million) at the box office.

Yamazaki said that the movie will likely be an important one of his career.

"I was so excited to act as Shin but there was also pressure because it's a very well-known manga series," he said.

"But just like Shin, all I had to do was put in 100 per cent of my effort all the time."

Kingdom opens on June 20.