SWEET! ^^ I actually didn't understand this one besides the line "kono mori". Anyway...

To "become dark", it would be "kuraku NI narimasu"... you could change it by putting "kuraku ni naru yo" (naru is the informal form of narimasu) and it would keep the syllables I think. Usugurai means gloomy? I'll remember that. ;)

I'm no expert in Japanese but the translation flows well...good job on your first one!

K :-)P.S. Does the original version follow the syllable rules? --jus checkin

Beautiful detail.Keep up the good work.

Much love,Juliet.