However, the court was told that the man had previous convictions, and had previously served time in prison, for offending against two other girls aged 10 and 12, and a 15-year-old boy.
He was already on the child sex offender register and had received two warnings under the now-repealed three strikes law for serious repeat offenders.
The man's name cannot be published to protect the identities of his victims, some of whom are related to him.
Crown prosecutor Clayton Walker argued for an open-ended sentence of preventive detention, saying the court was dealing with someone who had "deep-seated issues" and who would remain an ongoing risk to the community without successful treatment.
But defence counsel Sheila Cameron said preventive detention would be "premature and disproportionate".
Her client clearly posed a high risk of reoffending at the present time, but he had never been offered treatment.
According to a psychiatrist's report, he may pose no risk on release after going through prison-based programmes which were considered the best treatment, she said.
"He appreciates his own actions are morally repugnant," Cameron said.
Justice Jillian Mallon sentenced the man to eight years and six months in prison, with a non-parole period of five years and six months. This means he cannot be released until 2028.
She gave him credit for his guilty pleas, which meant that his victims did not have to go through the trauma of giving evidence in court.
She said the man had been the victim of abuse himself when young and had grown up in a chaotic environment where he was not taught about appropriate sexual boundaries.
SEXUAL HARM
Where to get help:
If it's an emergency and you feel that you or someone else is at risk, call 111.
If you've ever experienced sexual assault or abuse and need to talk to someone, contact
Safe to Talk
confidentially, any time 24/7:
• Call 0800 044 334
• Text 4334
• Email support@safetotalk.nz
• For more info or to web chat visit
safetotalk.nz
Alternatively contact your local police station -
click here for a list.
If you have been sexually assaulted, remember it's not your fault.