Square Enix Software Engineer, Backend interview questions

I accessed the local agent who recommended me to apply for this position in this company. There 2 video conference interview with Skype. Their time seemed limited so we negotiate it for times. The interview is not hard. Therefore, most of their positions are by contract by 1st year. After 1st round of interviews, their HR asked me to provide lots of data including my tax form to prove my income last year and they asked them detailedly. I provided my offer letter and part of the statements of the bank, and they questioned the problem like why the amount of my monthly salary was different by dozens of dollars? or asked me provided other cert to provide my onboarding date of the last job. I told my agent usually we only provide those data when they confirmed to give me the offer, and I didn't know what was the point they kept asking the amount I received in my account though they are different by little, it's not necessary to provide those sensitive data to HR for the candidates. I provided that just because I want them to have a reference to give me a reasonable offer. The 2nd round of interview is that some managers asked me the interest in other positions. For sure, they asked you the will to learn Japanese though the team I applied were composed by the foreigners.