A gorohachi chawan (五郎八茶碗) is the traditional vessel used for 'bata-bata cha' (ばたばた茶), a most intriguing dark tea from Toyama.
This dark tea is boiled and then whisked with a double chasen (meoto chasen | 夫婦茶 筅). The following video provides an idea of the concept.
<iframe width="560" height="315" src="https://www.youtube.com/embed/McVnPKvX2ic?controls=0" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
You can find bata-bata tea here: https://www.o5tea.com/collections/dark-tea-puer/products/bata-bata
Meoto chasen is sold separately.
