Visa advice so I can stay with my partner in Japan? We are lesbian, so marriage is not an option.

Hi everyone, sorry for any poor English, is not my first language,

I currently am studying in japan and have a relationship with my girlfriend for three years now. I am due to graduate soon in the spring and believe I may work for my family's company after I graduate (which would be remote/on the computer, so I could live anywhere I like). My visa ends once I graduate.

I would like to stay in Japan since I have developed such a life here, but I am struggling with my options. I have Korean citizenship, while my girlfriend has Japanese. If we were heterosexual, we would just get married so I could obtain residency. But since gay marriage isn't legal here, it seems like my only option to stay here would be to get a job for a Japanese company? Is there anything else? Is there anything that she could do since she's a citizen?

I haven't done much research yet, but am planning to do so. I was just curious to see if anyone had any advice or input.. I am very sorry if this question does not belong here or has asked before.. I am just very stressed out as I obviously do not want to move away from my girlfriend… Thank you for any advice 🙂