Sakaguchi Kentaro embroiled in cheating scandal with actress Mei Nagano while in a long-term relationship with girlfriend.

On September 9 (local time), Japanese outlet Shukan Bunshun reported that Sakaguchi has been in a four-year live-in relationship with his girlfriend, a hair and makeup artist three years older than him. The couple was even spotted visiting Korea together during his recent overseas activities.

However, the report further revealed that Sakaguchi allegedly began a secret relationship with top actress Nagano Mei about three years ago, despite being committed to his longtime partner. The two first met in the 2015 film My Love Story!! and later reunited in the thriller Masked Ward, reportedly building a close connection through their projects.

The scandal escalates as Nagano Mei herself has a controversial past. Just last April, she was embroiled in an affair rumor with married actor Tanaka Kei, who is 15 years her senior. While Nagano was once beloved for her pure and refreshing image in works like Half, Blue and Daytime Shooting Star, the back-to-back scandals have dealt significant blows to her reputation.

Fans expressed shock and disappointment at the news. Online reactions included: “This is more dramatic than a drama” and “Both had such clean images, I’m speechless.”

According to the report, even during the height of her rumored affair with Tanaka Kei, Nagano allegedly continued her involvement with Sakaguchi, further fueling public outrage. Insiders also revealed that while Sakaguchi often introduced Nagano as his “younger sister” to friends, he frequently dined with her in private — something that reportedly displeased Tanaka.

Both Sakaguchi and Nagano’s agencies have declined to issue official statements, but Japanese media predict the scandal may have lasting consequences on their careers. Sakaguchi recently gained significant popularity in Korea after starring alongside actress Lee Se-young in the Japan-Korea joint drama What Comes After Love. He was also scheduled to attend the Busan International Film Festival later this year, raising questions about whether he will publicly address the scandal.