Let me just aay, ID is full of weebs hence why a lot of them knows japanese. If we're going to rate JP fluency by ID members:
Iofi - very fluent in JP, has collabed with many JP vtubers in her early Holo days. She's also fluent in English and knows some Thai, German, Spanish, etc. Is currently on a monster fucking arc.
Reine - very fluent in JP, has done streams where she teaches Holomems how to speak Indonesian. Is currently on her lesbian arc. Also very fucking rich.
Ollie - very fluent in JP, has collabed with everyone, and I mean EVERYONE. Very intelligent and funny, also very menhera with noombers. Horny AF, will fuck anything that has a heartbeat.
Zeta - fluent in JP. Currently living in Japan. Is a cat that identifies as a secret agent. Has sexy thighs.
Risu - fluent in JP, has imposter syndrome. Has a very awesome singing voice. Could have been the breakout star of ID but decided to just chill and meme. Very based.
Moona - can speak and understand very basic JP. Fast learner, has big boobs and big everything. Still very pretty. Her pipes are Godly but not Risu-tier.
Kaela - can speak and understand basic JP, though a very fast learner. Autistic gamer. Kronii's ID wife. Biboo's guardian. Is currently cucking
@Negzana.
Kobo - can speak and understand basic JP. A literal child. The Gura of ID. Very entertaining. Joined Holo because a friend told her to audition and she passed. Great singer.
Anya - is a Japanese woman living in Indonesia. Do not be fooled, she is Japanese. She also knows English and Indonesian. Here's some clips that proves Anya is JP: