He told the court that the knife was in his hand when Tiepa-Ranapia came down the steps toward him. He said he punched a man with his fist as the man came toward him.
He was not aware that the man was Teipa-Ranapia and the man ran off.
He had become aware that someone had died on the following day.
Eruera was grilled by Crown prosecutor Greg Hollister-Jones why it had taken until this week to own up.
"You stabbed him," Mr Hollister-Jones said.
Eruera replied "I believe I stabbed him".
Mr Hollister-Jones said "you knew all along that you did that".
"No I didn't," Eruera said.
Eruera denied he had gone to the party intending to do violence.
He said he decided to own up to give closure to the family of Tiepa-Ranapia.
Eruera said he had seen the family in court every day and he felt their hurt and heard their cries.
"It is something I can't live with and they need this to move on and have better health."
The trial adjourned for the day after the evidence of Eruera because of a prior commitment by one of the jurors.
Eruera, who was also charged with wounding with intent to cause grievous bodily harm and assault with a weapon, was the only evidence called by the defense.
Hyacin Eruera, the mother of the woman who alleged she had been attacked, and their associate Paul William Taki will not be giving evidence.
They have also been charged with murder, wounding with intent to cause grievous bodily harm and assault with a weapon.
The trial resumes tomorrow with summing up by Mr Hollister-Jones and the defendants' lawyers before the jury retires to make its decision.
