Your Luka can be fairly understandable. I didn't catch the whole song, but I think I would understand with further listening. She has that girly kind of sound, like her japanese self, which I like XD As for the other parts, you can really hear the looping on the strings! Strings aren't hard to find, so I think you should be able to find something more suitable for free. The song doesn't have much sense of build, besides the synth near the end. It gives me a sense of falling apart, disjointedness, confusion, denial, which I like, but isn't strong enough to make the build on it's own. I think the song would benefit if you worked on the drums, because they're pretty constant. The ending wound down compositionally well, although the actual end of the song was cut unnaturally. I think you should have used a different illustration of Luka, because I've seen that one used before in a similar way, it's not very distinctive.
Overall, I say it has potential...I look forward to your future work 8O
