Japanese pop star Minami Minegishi has shaved her head as part of an apology to fans after she broke her record label’s rules and spent a night with her boyfriend.

The 20 year old, who is a member of the band AKB48, was recently reprimanded by her management team for violating its no-dating rule after she was photographed leaving the apartment of her dancer boyfriend, Alan Shirahama.

And now Minegishi has sought forgiveness by posting a four-minute video on her groups’ official website, during which she sobs as she cuts off her long hair.

Head shaving is a traditional form of showing contrition in Japan.

In the video, she said she had made the decision to shave off her long hair to show contrition for her “thoughtless and immature” actions.

“I don’t believe just doing this means I can be forgiven for what I did, but the first thing I thought was that I don’t want to quit AKB48,” she said.

At times sobbing and bowing her head during the nearly four-minute-long video, she also said: “If it is possible, I wish from the bottom of my heart to stay in the band. Everything I did is entirely my fault. I am so sorry.”

Minegishi was one of the original members of AKB48 when it was launched by producer Yasushi Akimoto in 2005. The band is made up of some 90 girls – whose ages range from mid teens to early 20s – who, in teams, appear daily in their own theatre and regularly on television, in adverts, and in magazines.

They portray an image of cuteness known as “kawaii”, and have become a huge phenomenon both in Japan and increasingly in other Asian countries, correspondents say.

Some fans and commentators say Minegishi went too far with her public apology, and that it was unnecessary.

“What’s the point of this public execution show? It’s like something from the war or a totalitarian state,” one fan said on Twitter.