shimen so ka
When I first came to Saga, I sat near a substitute science teacher with whom I liked to eat lunch and talk English/Japanese (and no, this isn't a typo, I mean it in the same sense as "talk shop") He would also teach me little Japanese phrases, most of them born in a military vein, which actually interest me a lot more than most idioms since I've always been fascinated with the wartime aspects of Japanese history.
...which is kinda ironic seeing as this idiom is 100% Chinese in origin. Translating the phrase strictly by Japanese interpretations of the kanji will leave you only with a bit of a meaning and none of the history. 四面 is changed easily enough to "on all four sides", but it's the 楚(briar/thorn) and 歌(song) that'll trip you up. So the thorny song from all sides might imply that you're either in a pinch, or - per American folklore - you just escaped Brer Fox.
1. To be completely surrounded by enemies on all sides, in a situation where no help will come.
2. To fight alone and isolated.
Chinese history lesson time! As a quick warning, this was meant to be short, but I got caught up in the research...
After the fall of the Qin Dynasty in 206 BC, the two major contenders for the throne were the Han - led by 劉邦(Liu Bang) - and the Chu - led by 項羽 (Xiang Yu). They fought for 4 years until 202 BC, when Lui Bang surrounded the remainder of Xiang Yu's forces in a canyon, which they had entered in order to rescue Xiang Yu's captured wife. By this point Lui Bang had already conquered a large part of Chu, Xiang Yu's homeland, and thus had many Chu troops in his ranks. He gave the order that all of his troops sing Chu songs, giving Xiang Yu's remaining soldiers the impression that the rest of their countrymen had already been conquered by - and even worse, subsequently joined - their enemies. It's important to note now that 楚 means "Chu" in Chinese, and thus it is "The Song of Chu on all sides".
Their spirits broken, most of Xiang Yu's troops fled on their own, and Xiang Yu's wife - blaming herself for having been the reason the army was caught in this trap - committed suicide. Xiang Yu was eventually able to break free with a tiny contingent of loyal warriors, but after countless misdirections, near escapes, and killing a few hundred men on his own (who refused to make mortal strikes, having been given the order to take him alive), he committed suicide.
Translation: Moving to a country where you don'tt speak the language can be scary. You don't have any friends, and your inability to express yourself in even simple terms can give you the feeling of being all alone. But the people you don't know aren't really your enemies, persae, so don't go shouting that everybody's against you. Just learn the language, make some friends, and it'll all be good.