Going to the karaoke box to sing is a very common pass time in Japan. You can go alone, you can go with friends, or you can sing in a bar with strangers. Whatever the sitaution you`re bound to have a good time! Recently, the Karaoke bars have more and more foreign songs (like English, or Korean) to meet the demands of tourists. So you`ll have no problem choosing at least one song to sing no matter where you`re from.
Most karaoke boxes charge per person, and sometimes you have to buy a drink.
The karaoke machines these days are pretty high tech. You can change the pitch of the song, add some reverb, do a singing challenge (where the machine judges your singing), and plenty more.
Sing your brains out and a karaoke place! Look for the カラオケ signs.