Description: As misleading as it may be, a "pub" could also be equivalent to a "snack" or "kurabu," i.e. one of the relics of Japan's bubble years, likely staffed by the same mama-san the entire time it's been open. It will be easy to distinguish between this and the British-style pub once you actually see the place.
System: If it's a snack setup, you'll generally pay a set price for a set time, which includes all-you-can-drink and all-you-can-sing karaoke. However the drink menu will probably be limited to one kind of cheap shochu, and that's it.
Budget: Expect to pay 3000-5000 yen per hour, more if you get talked into buying drinks for staff.
Making friends: You probably won't make any genuine ones