Reservation
Reservation is allowed up to 2 weeks in advance. Take note of their closing dates and decide on the meal that you would like, tea or dinner.
From the home page, click "ご予約"
Click on the button pointed by the red arrow. You can read through the 'English Guidance' for the rules of the reservation.
Select the date and time and number of guests visiting.
Key in your details
I'm afraid to click the confirm button in case it is the last step to reserve. Anyways, your reservation is only confirmed once you receive a second email from Swallowtail.
First email indication temporary reservation
Second email containing confirmed reservation details
And the reservation is done! Their reservation can get popular since I initially wanted to book for their dinner. But by the time I went in, I wasn't able to get a suitable date for dinner so I ended up booking for tea instead.
Dining
This is the only picture I have >.<
Upon telling the butler of our reservation, we were brought into the restaurant. We saw people waiting outside, maybe they don't have a reservation? We were brought to a place with lockers and the butlers proceed to take our bags and coats to hang and put inside. Essentially, you will end up entering the dining area with nothing except your own self :/
The dining area looks very grand and elegant; definitely makes you feel like an ojousama despite us feeling a bit awkward with the attention and trying to be prim and proper >.<
We had the afternoon tea, Victoria set I believe. If you want to eat the other item or have your tea refilled, you are supposed to ring the bell on your table and the designated butler will come and serve you.
The food was delicious, if only we could have dinner. Hopefully next time! Oh, and you have a timing assigned to stay in the restaurant. The dining time is longer for dinner but I don't recall how long already. We saw a Japanese lady conversing with her butler as well. I guess they don't want guests to take up too much time inside.
Map: Located at the basement down these steps of stairs