Creepy fun with an all you can eat option. The music is a little strange (1980s American Pop) but the atmosphere is all in good fun. Be admitted into the psychiatric hospital by nurses and sit in "cells" while costumed people come try to scare you mid meal. The food is good but not amazing but go on the weekend to catch a floor show and get the most entertainment.
Leave Shibuya subway station by way of the shopping area--down an esculator. Turn right and climb up the hill--past the major part of the Love Hotel section until you reach a 7-11. Take a right and go about two blocks. Its underneath something like Darts Cafe.