Help making an E>J poem translation fit a syllable pattern?

[EJTranslations]

An acquaintance of mine has requested a bit of poetry translated from English to Japanese for a project she's doing. I've dashed off a prose translation as follows:

いつかは死ぬと分かる
私を見えずに
すれ違う人
蝉のように
はかない一生を通じて鳴く

However, she wants it in 5/7/5/7/7, and I'm having trouble trimming it down. I would very much appreciate any advice.

I'm not including the original text since I think she'd rather I didn't spread it around, but I am happy to clarify what I'm trying to get at. To clear up in advance a few points that are vague, the "people passing by" are meant to be plural, and the speaker -- who is a ghost -- knows that they will someday die (not that she will, since she already has).

Thanks in advance!

[LavaBug]

I'm not entirely sure it's all grammatically correct (or in any way correct at all) but I give it a try:
How about shi beki hito (死べき人)　for the first line
in the second line pehaps just cut the "ni" at the end
I'm not sure what "sure chigau hit"o is supposed to mean exactly if that's the 'passing by' part how about just:
過ぎ行ける (subject being still the people from before...this implies the passing by of humans, also means dying in a far sense...according to dictionary)
as for the last part I'm rather out of ideas...my best try would be to forego the cicada part (never thought *I* said anything about ignoring cicadas though :P) and go for something like:
zutto (or itsumo) hakanai 　ずっと儚い (could also be "naku" instead of nai...I think it would make it more lyric...'ish...but nai sound better here imho)
sei wo nageku yo 生を嘆くよ(the yo is for emphasis also the make the syllable count complete :P)

Hope that helped at least a bit...If not, it at least distracted me from cleaning up my room ^^°

[animeyay]

The MAIN problem is that you're trying to squeeze waaaaaaaay too much information into just 31 syllables. Japanese, being the very polysyllabic language it is, would require a lot more syllables to express something as poetically elegant as what you have there. So, trimming away a lot of its beauty, I'll give you what I have:

ひそやかに
わたしが見てる
ひとびとは
ただ生きていく
いつか死ぬのに

Yes, I know it probably sounds like kindergarten Japanese compared to your original. I got rid of the cicada simile as well as "unable to see me" part. But like I said, there's just no possible way to keep it short AND elegant at the same time...

[EJTranslations]

Thank you both! I know it's pretty impossible to cram all that information into a poem this short; I'll have to explain this to the person I'm translating for and see whether the structure or the content is more important to her. Regardless, I really appreciate your suggestions and will take them into account.