Ms Shiino had proudly announced on social media that she became a naturalised citizen of Japan in 2022
The 26-year-old Karolina Shiino was crowned Miss Japan two weeks ago but her win sparked public debate due to her heritage.
While some welcomed the naturalised citizen’s crowning, others said she didn’t represent traditional Japanese beauty ideals.
Amid the furore, a local magazine published an expose alleging an affair.
The article in the Shukan Bunshun reported that Ms Shiino had engaged in a relationship with a married influencer and doctor. The man has not provided any public comment.