Then we got distracted again by Reading Stuff on the internet. That's usually not a good idea for us, but there was some fascinating material, including some manga reviews. See, back when we were reading every review we could find of Missions of Love, there was one that mentioned how it only uses a little bit of slang, and we could not figure out if that was supposed to be a good thing or a bad thing. (And just about every review we read of something we translated says something like this in regard to the translation itself, "Reads fairly smoothly, not too much slang, keeps all the honorifics.") But now we have found a review (of something else) that has finally answered the question, and now we know...well, actually I guess we don't know, because this is only the opinion of one person. But she seems to be in fan communities and share many fan opinions, as well as being on the more reasonable side of the "I can't believe they ruined it!!!!" spectrum.
So apparently a lot of fans think it's bad for a translation to have too much slang. I think that this is actually a pretty terrible criteria to base translation quality on, for one very important reason: the Japanese language has slang, too. And manga characters use it. The trick translators face is figuring out what kind of slang is appropriate and when. I mean, obviously it's going to depend on the characters. Taking Missions of Love as an example, Yukina's probably not going to use a whole lot of slang herself, but she observes people enough to know how it works and so ideally she incorporates it into her writing. Akira would use the basic slang that everybody uses, like "cool" and stuff like that. Mami would probably use a lot of slang, but only insofar as it fits her girly personality, and with Shigure it really depends on his audience.
...As for their actual use of slang, I really don't remember most of their exact lines, so I couldn't say for sure. It's something we don't usually spend a lot of time thinking about--usually our main concern is to convey the meaning and character voice, and sometimes that involves slang and sometimes it doesn't, and to be honest, neither of us is always even aware of when we're using slang ourselves. I know that "awesome" is slang.
We're constantly talking amongst ourselves as I write this, and so I was going to go on to use Saiyuki as an example of slang in Japanese (most notably the discussion about chou and geki), but then we were talking some more and remembered a point that would be more helpful.
The example of a horrible inclusion of slang in the review we saw was that a character said, "This is 100% totally awesome!" Okay, so we know totally and awesome are slang, and we're pretty sure we wouldn't have translated whatever was said that way, but we're not sure how that constitutes something, like, totally radically slangy, or some junk. (It sounds better in a valley girl voice.)
Our theory is that the problem is not slang. The problem is that nobody talks like that. The thing about slang is that people use it. There was a time, back when we were very young, that I was so determined to be...I don't know what I thought at the time. A nerd? Smarter than everyone? But the point was that I was determined that I would not use slang, even the word "cool." I don't know what I was planning to use at the time. Maybe "great" or something. (Athena suggested "wonderful," and I was like, "Yeah, nobody talks like that, either." Her response, "Yeah, because everybody uses slang!") And then our cousin introduced us to the Teenage Mutant Ninja Turtles, and that was the gnarly end of that, dude.
So yeah, of course we're going to have some characters use slang. When a guy in manga says "sugee," chances are we're going to translate it to "awesome," because that's what the guy means. But the trick for translators and adaptation writers is to make sure it's slang somebody would actually say, and in particular slang that somebody who is that character would say. Of course it gets really fun when a character uses slang in a way that's supposed to sound unnatural, and so you have to be able to tell the difference there, too.
Today I'm thankful for finally figuring out what reviewers who talk about the slang in a translation mean (we think), having Thin Mint Crunch thingies to try, getting a tiny bit of work done despite all our distractions, Disney finally releasing The Many Adventures of Winnie the Pooh on Blu-ray, and having time to finish this post before Athena leaves to go visiting teaching.