score:7
Completely illegal. All you need is one phone call to immigration and that place will be raided. This is not volunteering, but real work -- 2 pm to 10 pm?!? Really?!? -- and while payment is in kind rather than in cash, it is still payment. And quite a cheap payment at that.
A tourist visa in Korea does not allow you any kind of work -- paid and unpaid. This is clearly in violation of the law.