Getting part-time job without working visa

I'm a young woman (24 y.o.) who's planning to spend some time in Japan while doing volunteer work via HelpX website. As the job is volunteered, I won't get paid with money so I was wondering that is it possible to get short time part-time jobs (e.g. babysitting, dog walking, leaf letting... etc.) so I could get some pocket money? Or is this illegal/impossible to do? I would be staying with tourist visa (3 to 6 months) and I'm quite sure I won't get a working visa as I'm not a high school/university graduated.

Thank you for an advance! :)

It is illegal to do any paid activities on a tourist visa. That includes part time jobs such as babysitting.

It may or may not be possible to apply for a work permit on temporary visitor status (no "tourist visa", please). By law it should be possible, but on the immigration bureau's website it says that you need to submit your resident card when applying for it, and if your status is TV, you don't have one...