You can find bottles of yuzu juice in Japanese or Asian markets. (tastingtable.com)
When my dad told me that he had a ton of yuzu juice from their harvest (they've been making marmalade and jam) I really wanted to try making yuzu curd. (sweetcinnamonhoney.com)
** I actually used yuzu juice for this inaugural batch, because I had a bottle on hand brought back from Japan by my friend Chika - san. (cnz.to)