IT job in Osaka

I was lucky enough to got naitei for an IT job in Japan. I don't have much experience about working in Japan yet so can someone please tell me. Is it hard to change job in Japan when you have 2 years of experience? What they will ask you and how you can answer the hard questions like why you change job? Is it hard to relocate? Because my company are in Osaka. I don't think there would be much opportunity there so I have a plan to get a job in Tokyo after 2 year. Thanks very much