No worry, such limitations are not written on their web site,
and you can find some male customers are also shown in the photos, open URLs again.
But in Japan, plum wine(梅酒 ume shu) and fruit liquor(果実酒 kajitsu shu) in this bar are NOT sake(酒)
that most Japanese men like to drink, it means more than 90% is female customers.
BC most Japanese women drink while worrying about drunkenness, health and last train.
Japanese men do not dislike fruit liquors, a ton of "wine(ワイン)" lovers existing.
"梅酒" in English the word "wine" using, but strictly the making method is different.
This is homemade "how to", https://youtu.be/emgHzVoJCUc
but the taste changes not only the quality of plum seeds, but also by the type of alcohol and sugars.
However, "梅(ume)" is not strictly the word "plum" as botany,
it is better to use "Japanese apricot liquor" but too long and also the word "apricot" is not 梅,
so "ume shu" as loanword like "karaoke" and "Pokemon" is the best but it seems that it is too late.
Anyway, their bars have also beer(ビール) though, but no wine and no enough food menu for hungry man.
If still wondering you should send e-mail ASAP. (contact mail)