Crown prosecutor Joshua Harvey said the girls, who were in Oranga Tamariki care, lived with the man and his partner for some time before the incident in April 2019.
The girls were indecently assaulted on their first night back at home after some time away, Harvey said.
They were picked up by an associate afterwards, while emergency services were called to get the man, who spent the night at a police station.
He told police the next day he had no memory of the event but he did not doubt what the girls said and would not blame alcohol for what happened, Harvey said.