Photo: YouTube / AKB48

Japanese popstar Minegishi Minami has shaved her head after she was caught spending the night at a man's house.

Minegishi is a part of Japanese girl group AKB48, who are considered 'idols' in Japan and, as such, have a 'love ban' - which means they can't date or have sex.

After a weekly magazine published reports that Minegishi had spent the night at Shirahama Alan's house, Minegishi posted a video online explaining that she had shaved her head in apology, and hoping that she would be allowed to remain in the group despite breaking the rule.

In the video, Minegishi says, "I’m Minegishi Minami from Umeda team B of AKB48. I'm very sorry to have caused enormous worry to members, fans, staffs, my families and a lot of other people with the article in the weekly magaizne that is published today.

"As the 1st generation member of AKB48, the group that has formed in 2005, it's my responsibility to always behave as a good role model to juniors. I deeply regret what I did this time. It was a thoughtless deed and I was completely lacking self-awareness as a senior member.

"My brain blanked out and I'm still unable to figure out what to do, what I can do. But after I saw the magazine a little ago, I couldn't help but doing something. And I decided to shave my head without consulting any member or staff at my agency. Although I don't think I would be forgiven by doing this, the first thing that I went through my head was that 'I don't want to leave AKB48.'"

Watch Minegishi Minami in the video below:

She continues, "This is a place where my dear members, who I spent my blossom of youth together, are. And it's unimaginable to even think about leaving the group where I'm with so many wonderful and sweet fans. I understand it's wishful thinking, but if it's possible, I would like to still be AKB48's Minegishi Minami.

"This is all my fault. I'm truly sorry. I will leave my hereafter to the hands of Akimoto-sensei and management. Though I haven't been able to tidy my mind up, but I just wanted to tell my current feeling to you. Thank you so much for listening to me."

AKB48's management released a statement saying they are 'demoting' Minegishi to a lower level of the group.

Below - behind closed doors: rock and roll sex secrets