For what it's worth, I started my own translation firm two years ago (after working in-house for over a decade) and I charge anywhere from 16 yen/character (pretty much my minimum, for stuff that like Majestic says can be at least partially automated, or for "friendly discounts" to people I know for non-urgent) to as much as 30 yen/character for more specialized or high-priority (quick turnaround) jobs.
I'd also agree with Majestic that 20 yen/character is a good base rate to start negotiating from, though I would add a caveat that it's going to depend a degree on the industry and what sort of reputation/track record your friend has. I've been pretty successful in not having to undersell myself (or undercut my competitors), but that's in part because people in my primary field know me and they know they're paying for quality work rather than just a glorified machine translation.
Majestic said:
HOWEVER, Google translate is getting better day by day. I imagine in ten years it might be quite useable.
Maybe I'm being too much of an optimist, but at least in my field (which is more on the creative/literary side), I haven't seen anything to suggest that machine translation will become viable any time soon. Google Translate and DeepL have improved quite a bit in recent years, and they can do a decent job (still requiring a heavy native edit, of course) with dry technical documents, PowerPoint presentations consisting of mostly business terms and short phrases, etc., but they still don't even come close with colloquial or archaic dialogue, stylized speech patterns, translating puns/jokes/wordplay, etc.
To Lothor:
Anyhow, as a fellow translator, I wish your friend the best of luck in her new career (and if she's ever available to take on a side job here or there, you can even put her in touch with me if you'd like

)
mdchachi said:
There are lot of people translating on fiverr. You can also look there for reference. For example this Level 1 seller charges $5 for 250 words.
No offense, but anyone who is translating on fiverr for such an insultingly cheap rate is almost certainly not a professional translator and could very well just be plugging things into Google and sending them off to people who don't know better. No self-respecting translator should be looking to compete with these people and their rates any more than, say, a professional musician should be looking to compete with a person who plunks around on the piano in their spare time.
(edited for formatting)