Hmm. Interesting problem. I'd offer to help, but my knowledge of japanese isn't that brilliant, and I would say the poster above me understands it much better.
I was wondering about some of those translations though... It's funny when you know some of the words but can't think of them then and there.
I based a username on the word 'kurai' once... Though it was combined with gibberish to make something that sounded interesting.
Of course, given how I wrote it, that usually resulted in people calling me kura.
(It's quite amusing when you look this stuff up sometimes, because while I started from 'dark' - kurai, the end result of the name I chose, and the way it usually got shortened meant... kura - 'saddle' (or alternately, 'warehouse')
There's definitely subtleties of translation that can trip you up. Then again, I chose a word based solely on how it sounded, not what it meant in the original language.
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Ok, in a slightly more useful context, let me use my limited knowledge to double-check Toriver's translations.
Ai no kurai Tenshi.
OK, so
Ai - is 'love', in the romantic sense, usually. (I haven't seen it used in the English sense of for instance "I love icecream".)
kurai - means dark
Tenshi - I don't recognise this off the top of my head, but a quick check of a dictionary does translate it to 'angel'
no - Is a grammatical particle usually indicating membership of a group. Due to the grammatical rules of japanese, the 'group' is in front of 'no', and the object that belongs to the group is after it.
So: Ai no kurai Tenshi
Taking it literally as written:
Love (of) dark angel
But keeping in mind the difference between english and japanese grammar, it becomes:
dark angel of love.
Ok, so... Out of interest, I'll take a shot at what "Akuhei Aijou Mitsukai" means.
akuhei - I can't find this in my dictionary, but taking into account that 'aku' means evil, and various similar sounding things such as 'akusei' (meaning malignant), 'akuma' - devil, 'akumu' - nightmare, 'akunin' - villain and 'akutai' - verbal abuse/swearing...
Collectively this suggests 'aku' has the meaning of bad/evil. - That's a possible translation of 'dark', but only in some limited contexts.
Aijou - the romanisation of the last part varies in different dictionaries, but this is a variation on 'ai'. This particular variant is listed in my dictionary as affection or 'love', but since that overlaps with 'ai' in general, that suggests different uses depending on either grammar or context. (I personally don't know enough japanese to know what the distinction would be in this case)
mitsukai - Is a word I can't find in my dictionary, nor can I find similar words that make any sense in context, nor break it down into components that make any sense. I'm at a bit of a loss as to what it means. - That's not to say it doesn't exist. My dictionary isn't exhaustive, but it does raise the question of what it means and how common the usage of it is. (as well as the context in which it is typically used.)
In any event, Toriver seems to have a fairly decent understanding, and translations that seem to make sense.