karaoke bar is located further north of the city. You can go to the map and press the triangle to see a list of companies. Once you have purchased 60% of the shares in the area, Leisure King Marina will leave a message asking you to meet him at a karaoke bar. You need to meet with him before you can make any further deals.
I was just looking at the grocery stores, it never occurred to me that the karaoke bar would be an entertainment store. Go to the karaoke machine in the bar of your choice and you can check the rankings, your history, etc.