Question about Studying, Investor Visa and Getting there

Hi,

Me and my gf recently visited japan, osaka to be precise and absolutely fell in love with it, we are both in our early 20s and its been a dream of ours to escape England and get to Japan someday, hopefully permanently.

Now, I've come into a lot of money in the past year, essentially retirement amounts, so obviously making that dream a reality is something that seems possible now.

We've been looking into going for two years to Kansai College for their two year Japanese course initially to make sure we are actually cut out to stay in the country, from what we've seen its pretty valuable and obviously knowing the language is essential, one thing that confuses me a bit though (forgive me if I'm being stupid) is that it says you can go on to a third year of university, now does this mean you do 4 more years of study to get your bachelors or do you just carry on for two more?

After this we would find work or something along those lines.

The other option which seems like a bit of a headache but an exciting opportunity is the investment visa, running a business would be challenging but amazing at the same time, its just the startup that seems a headache, would it be difficult for us to set up a store? Does anyone have experience in this sort of thing? I mean we saw tiny little Turkish kebab shops there so it can't be THAT hard if they're doing something right?

Excuse the wall of text but we are just brainstorming different avenues we could take due to our flexible circumstances but aren't sure what the best route is to take, with some people recommending against the language course for some reason