On full-time employment but working less?

I work at an all-inclusive skiresort at Hokkaido.
I work as a full-time employee, however my contract does not prescribe any workinghours (all though it says that there is work beyond the prescibed hours)
I have a basic salery per hour (minimum wages).
My workposition is �gservices at the hotel�h. First I worked in the restaurant but transferred to Takkyubin/piccolo due to management issues. In the restaurant I worked 8h. The first 2 weeks as piccolo I also worked 8h, but now it has become more the rule that I (and my two co-workers) work 6,5 or 7,5 or 7 or 5,5 hours etc. and rarely 8h.
Hr tells me that it�fs not a problem (nor a legal one) but I find it hard to belive that full-time employment is less than full-time (8h/day)
Can I do nothing (legal) to assure that I work 8h/day? Are they in their right and I�fm just being used/misused to their advantage?

What kind of contract do you have? Does it say full-time work, with (monthly) salary specified, based on 8-hour, 5-day week, for example? Or does it specify (hourly) pay/wage only, with no hours determined? And if you work only 5 hours (even if it was due to hotel management�fs reasons), you get paid the full monthly salary or only the hourly wages for the hours worked? Does it specify when the overtime starts, for example does it say �gyou get 25% more overtime pay if you work over 7 hours a day�h (8 hours at work place, minus 1 hour break) or something like that?

What kind of work-permitting resident status do you have? I am somehow assuming Working Holiday, because of the pay and the types of services you are doing (if you can move between restaurant work and Takkyubin service, that means you cannot be a chef, for example).

If it is Working Holiday, it is supposed to be system which allows young people to travel extensively in another country (in your case Japan) while allowing them a way to earn pocket money to help with travel expenses, so that sounds possible that they wrote the contract to allow �gwages�h instead of monthly �gsalary,�h and have it set up so that they can reduce the work hours and pay only for the hours worked.

generally speaking, when your work is more than 3/4 of seishain, your work is considered as a full-time.
when seishain (no limitation about the hired term, except for the retirement) work for 40 hours per week, you are a full-time worker when you work more than 30 hours per week.
that is the reason why students can work up to 28 hours/week with permission.

My contract states:

1 Period of employment with a fixed term; From November 24, 2019 to April 12, 2020.
2.1 Renewal of this agreement (not relevant for this thread)
2.2 Determination on renewal (not relevant for this thread)
3 Workplace; Club med Sahoro
4 Duties; Services at the hotel.
5.1 Time for starting and ending work and the rest period; Time for starting and ending work and the rest period shall be as stated in the appendix, List of Working Hours, and the details of work will be determined no later than seven (7) days prior to the day on which the work starts and informed to each worker using a work shift table, provided, however, that such day may be moved forward or backwards for the convnience of buisness or other unavoidable season.
5.2 Work beyond the prescribed hours; there is such work.
6 Days off; Days off shall be two (2) days a week and determined specifically according to the shifts in each department.
7 Annual paid leave; After continuous service for six (6) months, annual paid leave will be granted to workers who have repported to work 80% or more of all working days as prescribed by law.
8.1 Wages and allowances; Basic salery 950 yen/hour
8.2 Premium wages; (not relevant for this thread)
8.3 Deduction for wages; (not relevant for this thread)
8.4 Date of payement of wages; (not relevant for this thread)
9.1 Matters of resignation procedure for voluntary resignation; (not relevant for this thread)
9.2 Reason and procedures for dismissal; (not relevant for this thread)
10 Participation in social insurance; Worker shall participate in the following social insurance if it is necessary under the relevant laws and regulations.
Industrial accident insurance, employment insurance, health insurance, and emplyees' pension insurance.

(ps. I handed in a letter of resignation just before christmas (resigning 22 of Jan.), but was then offered a new position as piccolo, yet I noticed that HR kept my letter of resignation)

Mmmmm. As far as I can read off this, it sounds like a typical part-time work contract, like any student might get working at a convenience store. The hours are not �gfixed�h in the appendix either, I assume, and you do get notified of the work shift 7 days prior, as described? Then I don�ft think there is any legal issue.

They showed me the appendix when I signed the contract but didn�ft give it to me. I�fm asking for it now (but HR says there is no appendix)
The schedule is 1 day before, but now because I complained, we get to see the �edraft shifts�f 4-5 days ahead.
(in the restaurant it was made on a 10 days basic, so day 10 you disn�ft know the schedule for the following 10 days)

it is definitely bad way that you write the company name to this forum.
even if you believe you are right, still you should not do that. I think that is common sense in civilized countries. it also unintentionally makes this forum involved in the argument. and you have risks that you will be sued and be laid off.

I think you are hired as one out of many seasonal workers, please think more seriously your situation that you may be not an indispensable person for them.

I imagine guests staying in Hokkaido must be on the decline, so the company would want to cut down their expenses (I am assuming you are getting paid by the number of hours worked). With this new coronavirus scare, any business in the hospitality industry can face financial difficulties, and if the company claims that they had no choice but to reduce the number of work hours for the seasonal/part-time workers, their assertion is likely to be accepted, unfortunately.

And your contract is only until April, so they are likely to just drag it out till you leave. This is my take of the whole situation. So if you still have some time left on your working holiday and can find another employer to go to, you might want to do that. If it is near the end of the working holiday as well, I might just hang in there.