よん じょう はん趣味 しゅみであれば
yonjōhan shumideareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of 四畳半趣味

1. If/when it were a four-and-a-half tatami mat hobby:; If/when one had a four-and-a-half tatami mat hobby:

Ba Conditional