SEOUL • With the German national known only as Josh staying put in South Korea in a bid to fulfil his mission of meeting Twice singer Nayeon (photo), the girl group's agency is stepping up its moves to protect her.

According to various Korean media outlets, agency JYP Entertainment issued a statement on Wednesday to say it has filed criminal charges and a restraining order against the man who wants to marry the singer and settle down in Australia.

Josh, 25, who returned to South Korea last month after an earlier visit, had a shouting match with Nayeon's bodyguards on Jan 1 after he took the same plane as the Twice members. They were returning to Seoul from Japan after filming a special for a broadcaster.

The bodyguards managed to foil his attempt to talk to Nayeon, 24.

But the incident unsettled the singer, who later posted online: "Please go back home. Please stop. I beg you."

Josh, who said he is not a stalker, has insisted he just wants to give a letter to her and that Nayeon's managers should give her a chance to hear him out.

JYP has also said Nayeon and other Twice singers are now under police protection.