I've never been to Ireland, so I don't know what a REAL Irish pub looks, feels, and sounds like.
I have, however, been enjoying this series by @eroche in which he explores a number of Dublin's well known and not so well known pubs: The Irish Pub & A Dirty Old Town. Having read quite a few of these now, I think I can safely say that Irish pubs in Japan are quite different from their counterparts in Ireland.
A version of the Irish pub has been exported all over the world and from Mozambique to Shanghai you can visit a "Molly Malones" or "Murphys". Each incarnation will have an Irish sounding name and be distinguished by Celtic writing above the door but there is no substitute for the real thing.
While there may be no substitute for the real thing, variations sometimes have their good points. Let me introduce you to one.
The Nomihoudai 飲み放題
Pretty much all Japanese restaurants, bars, pubs, and izakayas offer some variation of this unique and, to be honest, unbelievable, drinking option. It is a set price, limited menu (no top-shelf stuff), all-you-can drink option called a nomihoudai (No-me-hoe-die). Maybe you've heard of it before.
These nomihoudai are governed by time limits, usually one, one-and-a-half, or two hours, and they are very reasonable. A basic rule of thumb is that if you are going to have more than three drinks (soda is included in this), you might as well order a nomihoudai plan.
For example, Liffy's, the Irish Pub that I visited with @kafkanarchy84 the other night sells beer for between ¥500 and ¥800. If you want a full pint of Guinness or Kilkenny, it will cost you ¥900. For the price of ¥1,650, though, you can drink all of the beer (not including Guinness and Kilkenny), shots, and cocktails that you want.
For ¥3,000, you can drink all the alcohol your heart desires while also eating a five-course set menu that includes a salad, fish and chips, a sausage and a spare-rib plate, and more.
Not only that, if you really need to drink that Guinness or Kilkenny, after all, this is an Irish Pub, you can pay an extra ¥1,000 and have those beers included in your drinking options. That means ¥4,000 for a decent dinner, a few pints of Guinness, and a whiskey or two as you like.
Does that sound too good to be true?
Basically, it is. It is an incredible deal and a great option to have when you want to have a few drinks with friends but don't want to break the bank. It is also a bit of a dangerous option because, as you can imagine, it's quite easy to drink more than you planned. I often think that the nomihoudai begins as a gift from heaven to newcomers in Japan and turns into a gift from the devil to those of us who stick around long enough to start getting old here.
As with all things, moderation is the key.
People often describe Japan as being expensive and having a high cost of living, but there are a lot of built in life hacks here, like the nomihoudai, which help to keep things, in my opinion, very reasonable. No tipping is another example.
While you might not find live music in the Irish pubs across Japan, and while you probably won't find many small, parlor-like rooms that are good for having conversations and sitting alone in that many of Dublin's pubs appear to have, you will find the characteristic dark wood interior, Guinness on tap, and a good mix of whiskey options. In addition, of course, you will find a nomihoudai option on the menu as well.
Maybe @eroche can push to have this system implemented in the pubs of Dublin.