What happened in the end anyway?

In the end Yukuzi was jigoku shoujo for one episode ... Ai's job was to prepare her to become the new jigoku shoujo , after Yukuzi failed the Demon spider tried to send her to hell . Long before Yukuzi died at the age of 8 or 9 ,, but came back some how to be a middle schooler , this is why in the series she cant remember her child hood , but strangely in some episodes she talks to her parents which also died befor her ... Ai finally puts her soul to rest by relieving her duty of jigoku shoujo ... Akie's dad kills him self and her made that was in love/ with him kill the girl who killed akie .. ... I feel like theres definetly gonna be a season 4, where some how she finds away to kill the demon or finally rest in piece