Hey, sorry for not noticing this post earlier.
I think you've got a good voice for ballads and you're making a good effort conveying emotion. If you find joy in doing it, then keep doing it for as long as you can!
Did you translate the lyrics directly from Japanese or come up with something totally different?
Since you asked for some constructive tips, I have a few. I'm not really a vocalist myself, so take it with a grain of salt, and please don't take any of it the wrong way.
-Your intonation seems to be good once you're in the middle of singing a passage, but sometimes the first few notes are a little off ("If it's possible" at 3:06). If you play any instruments, I suggest playing the notes you're trying to hit and singing over it.
-Sing a bit louder and project more confidence. If it's possible and it helps, try to find a time and place where you can be alone (I did notice the message that people were sleeping over.)
-If you have the means and are serious, invest in a good vocal microphone, like this one:
http://www.shure.com/americas/products/microphones/sm/sm58-vocal-microphone.
By the way, I've never heard this song before. This is solo Toshi stuff? What's the name of the album?