I think that you _can_ do it with a split:

perl -le "print for split /(?=[^~\/](?:.|$))/,shift" "E/sYna~ko/"
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looks as if it works on your test data.

Update Actually that should have been

perl -le "print for split /(?=[^~\/])/,shift" "E/sYna~ko/"
[download]

but you saw that