Kentaro Sakaguchi, the famous ‘Seo Kang Joon of Japan’, is currently making headlines for pretty scandalous reasons: Apparently, he’s dating actress Mei Nagano. While that’s not controversial in itself, reports have it that the situation he is involved in is a love triangle. Turns out, he had been dating Nagano all the while being in a relationship with his girlfriend of 4 years.
According to All KPop, citing Japanese weekly magazine Shūkan Bunshun as the source, Sakaguchi has been in a relationship with his girlfriend, a hair and makeup artist, for four years now. Although she is three years his senior, the two have been living together nonetheless.
However, Sakaguchi allegedly started cheating on his girlfriend when he reportedly began seeing top actress Nagano around three years ago, secretly. Per the outlet, the two first met a decade ago, back in 2015, during the filming of My Love Story!!! Their bond reportedly grew stronger when they reunited in Masked Ward in 2020.
How Kentaro Sakaguchi’s Reported Affair Started With Mei Nagano
Per further details from @cloverblossoms_ on X, both Kentaro Sakaguchi and Mei Nagano have notably collaborated on numerous projects over the years. In mid-2022, when they met again as PRADA ambassadors, the source alleges that they ‘quickly became close at a PRADA dinner.
At the time, Nagano reportedly went around telling everyone that Sakaguchi was pursuing her ‘like crazy’. The two are also said to have gone on a date, hand in hand.
Sakaguchi Kentaro and Nagano Mei have collaborated on numerous project. In mid-2022, they met again as PRADA ambassador and quickly became close at a PRADA dinner. She even told everyone around her that Sakaguchi pursuing her like crazy. They even go on date hand in hand.
This… pic.twitter.com/lL1d6P4QWg
— ハズキ 🍀 (@cloverblossoms_) September 10, 2025
Although he was still in a relationship with his longtime girlfriend at the time, an acquaintance of Nagano claimed that the actor ‘really wanted to end his relationship with [his girlfriend] and be with Nagano.’ However, because he was ‘indecisive’, he continued to stay in that relationship.
Insiders even claim that Sakaguchi often described Nagano as a “younger sister” and frequently went on to dine with her (per All KPop).
If that wasn’t enough, additional reports claim that Sakaguchi finally told his girlfriend about his relationship with Nagano. When he did so, she was, of course, not pleased with it and called Nagano and reportedly asked her not to come near Sakaguchi.
This Reported Love Affair is Further Embedded With Controversies
While this story sounds twisted already, there’s even more to gawk at. Turns out, Mei Nagano was also involved in an affair with Kei Tanaka, a married actor, around the fall of last year. While that scandal damaged her public image, the actress allegedly still had feelings for Kentaro Sakaguchi, even once drunk-calling Tanaka ‘Ken-chan’.
As per the reports, Nagano apparently continued her relationship with Sakaguchi even when rumors of her affair with Tanaka made rounds on the internet. Her frequently going out to eat with him even reportedly caused discomfort for Tanaka at the time.
To further make things even more perplexing, @cloverblossoms_ on X revealed that the hairstylist, who had been in a long-term relationship with Sakaguchi, previously worked as Tanaka’s hairstylist and makeup artist as well.
Reportedly, the spring of this year had Sakaguchi consulting his agency about his girlfriend of four years, who is said to have even wanted to marry him. However, Sakaguchi reportedly wanted to “focus on his acting career.” He even “made up his mind and broke up with her,” with the two “already living separately,” per the source.
Of course, this confounding turn of events is drawing massive outrage from fans worldwide on the internet, with the disillusioned fans’ reactions ranging from disbelief to anger. With that said, it won’t really come as a surprise if this scandal significantly impacts both the actors’ careers negatively.
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