I turned 26 this year and I want to start working in Japan while I'm still young, I understand how you feel at least.
You should be able to get a part-time job on a student visa as far as I know, but you're restricted in the number of hours. If you were only trying to get an MBA in Japan to increase your chances of getting a job in Japan or live there then I'd say it wouldn't be worth it, but if you would get an MBA regardless then getting one in Japan would definitely help you out when it comes to job searching at the very least. I don't know anything about the actual process though so I can't say much.
I don't think LinkedIn is going to be the best place to search for jobs in Japan unless you are looking for foreign companies. Maybe you could check out Wantedly instead. It seems to be kinda similar to a Japanese version of LinkedIn from what I've seen. The company I have an upcoming internship with actually has a lot of its staff on that website so it's been useful for stalking and getting some info before interviews and such.
You should be able to get a part-time job on a student visa as far as I know, but you're restricted in the number of hours. If you were only trying to get an MBA in Japan to increase your chances of getting a job in Japan or live there then I'd say it wouldn't be worth it, but if you would get an MBA regardless then getting one in Japan would definitely help you out when it comes to job searching at the very least. I don't know anything about the actual process though so I can't say much.
I don't think LinkedIn is going to be the best place to search for jobs in Japan unless you are looking for foreign companies. Maybe you could check out Wantedly instead. It seems to be kinda similar to a Japanese version of LinkedIn from what I've seen. The company I have an upcoming internship with actually has a lot of its staff on that website so it's been useful for stalking and getting some info before interviews and such.