Unpaid overtime wages and unpaid paid leave

Hi! I am currently 正社員 for almost 8 years now, going 10 years for being part-timer since.

I haven’t had much thought about this stuff, since they granted me working visa, but since I am planning to quit soon. I wanted to be prepared, and ask for advices before going to 労働局 and eventually to lawyer up.

From the start, I always work for more than 8 hours a day 6 times a week. Longest would be 13 hours a day. I am also under hourly wage basis, with shifting schedule every month. At first, no overtime wage pay was included in the monthly payslips, then maybe just 4 years ago, my hourly wage was splitted and turned into overtime wages. For example, initially I’m under 1500yen per hour, but then it became 1250yen because another 250yen was transferred to overtime wages to make it look “legal”.

I also doesn’t have paid leaves not until last year. Meaning, I didn’t have paid leaves for 6 years. Upon researching, I could ask them to pay maximum of 3 years worth of overtime wages charges plus penalties, and a maximum 2 years worth of unpaid paid leaves.

I was also deducted 3000yen whenever I called in sick. It is fair and legal that I don't get paid for the hours I don't work under an hourly wage system, but deducting an additional 3,000 yen from that is not legal right?

What are your thoughts on this? Please, I need advice.

by Smart_Fail4833