I love IKKYU! Its a super cheap izakaya to go binge eat and drink at! Also many many gays go there because its only a few block away form shinjuku nichome gay district. If you get the gold members card, you can get major discounts depending on the day of the month! Def recommended!!
"The driving concept behind Ikkyu is low prices, and it is certainly one of Tokyo's cheapest izakaya. Steep discounts - between 30% and 50% - are available if you are willing to become a member of Ikkyu. Anyone over the drinking age can become one. If there is a member in the group, the whole group is charged the member's price. Snacks are priced around 300yen and draft beer is 231yen (member's price). A good place for large drinking parties."
Check out their site info http://www.193.co.jp/ (japanese only)
English travel site info: