Description: Do you dream of becoming a drunk salaryman who takes off his shoes before splaying out on the bench of the last train home? Good, because it's the ultimate Japanese cultural experience. Bring your cheapest suit and a tie that hangs way past your belt buckle, since your night begins, and potentially ends at a tachinomi (figuratively "stand and drink"). Tachinomi are dirt-cheap local watering holes, most not much larger than a broom closet. Often found in salaryman-centric neighborhoods and/or under the train tracks. How is this different from a "standing bar," you ask? It's really not any different. However tachinomi tend to be more Japanese when it comes to their menu and clientele.
System: If you're lucky, someone will actually be there serving drinks. If you're even luckier, a public restroom will be nearby. Some tachinomi have no staff whatsoever, and consist of only a few vending machines and tables.
Budget: A beer from the vending machine is probably around 300 yen.
Making friends: Highly encouraged, assuming you like middle-aged salarymen.