Most host bars in Tokyo seem to quote ¥15000 = USD100, although some are 13000. More expensive than Thailand but remember no off fee, in most cases no drinks and absolutely no tip. You can also pay by credit card. Not at all unreasonable in my view. You may be asked for travel money which will be quoted in advance but only if your hotel is really far away from the bar premises. Worth remembering that subway and overland rail tickets within the Tokyo area are very inexpensive - 45-50 baht.
None necessary but thanks. What you describe is very much the Japan of 20 years or more ago. I decided to take a few days in Tokyo after changing planes there several times. The first time was a little confusing but thanks to a cute Japanese I met thereafter it was pretty easy.
It's certainly true that many bars will not permit foreigners. I believe that's for 2 reasons. 1) most bars are tiny accommodating little more than 12- 15 and most of them will be regular customers. I was also told the no foreigners rule is because the regulars may speak little or no English or other foreign language. The mamasans want to maintain harmony within the regular group. It seems few Japanese like to go bar hopping as we would in Thailand. They have one bar and stick mostly to it. 2) In many Japanese bars in addition to your requested drink you get a small snack. At first this seems very kind, until you get the bill and find you have to pay for it! Never heard of or come across restaurants being Japanese only.
On the other hand in Shinjuku ni-chome there are bars which happily welcome foreigners and larger bars open to the little streets (where snacks are not served).One of the longest established and friendliest for foreigners and Japanese who like to be with foreigners is the basement bar GB in the ni-chome gay bar district. Another is the oddly named Arty-Farty. Streetside there are several including Airro the cafe/bar. The vdo below has a Japanese and a western guy introducing various bars and other places in ni-chome, including one which now has go-go boys at the week-ends.
https://gb-tokyo.com
https://www.artyfarty.jp
https://tokyo.gaycities.com/bars/2112-aiiro-cafe