I love Jdrama too, that’s how I got into Kdrama. I saw quite a lot of them elsewhere. Would love to see more Jdrama on Viki. But I heard the license process for Japanese content is complicated. Not for Viki alone but in general Japan likes to keep things more for themselves so getting a license is hard and most likely when they are willing to give a license they ask a lot of money and come with a set of rules which might not work out. As for limited Japanese subs, I have a channel where eventually the Japanese subs where locked because the content owner did request it.
I had hoped that now Viki is Rakuten’s (which is a Japanese company) it would lead to more Jdrama on Viki but I guess not 