Question about Japan citizenship

Hello people ! I have some questions and doubts, I was wondering how hard is the citizenship process? Is easier than PR or harder? We had been trying to find it out with my wife "national" we had been married 2 years, I received already a 3 years visa, had been living in Japan for around 7 years already, 2 years as language student and 5 years as 正社員. Does the requirements for citizenship are harder? Because we had been reading that for PR we need to be married 3 years and having a 3 years visa, does requiments for citizenship are the almost the same?

Thanks for your time!