There's three JPs in Phase right now (Nasa/Michiru/Iori, though I believe Iori streams in English quite a bit too) and they have the smallest numbers in the company, but they're also not hurting anything by being there - they seem comfortable enough, they have their own regulars, and the other girls seem to respect them as much as you can through a language barrier. It definitely feels like Fishfag has no idea what to do about them though, they could really benefit from explicitly JP-centric marketing.
The more I think about it the more divided I am on whether I think Phase picking up the Chinchilla would be a good idea or not. A surprising amount of Phase's existing audience seem to have stuck around long after the initial raid which proves there are people who really like her (hell almost her entire chat are green right now), and a bigger platform could help her find an audience beyond just EOPs from Pippa's chat. I'd be interested to see how well she'd get on with the existing Phase JPs since all of her Phase interactions have been with Pippa and iirc Airi(?); while those cross-language interactions are cute they're more of a novelty, while joining a group with three other JP-speaking streamers could benefit all of them if they have a good dynamic in collabs together.