I’m only slightly familiar with the J-Pop, so I can’t make any comments about the specific style.
The piano is nice, and the solo cello very effective. You’ve got some nice builds in the song.
Really nice stereo balance!
The guitar solo works well, but is just a bit too precise. The guitar fills behind the vocal are quite nice.
The vocal sounds great. My only complaint is very small - on the very last syllable, it sounds like like the volume is being turned down mechanically instead of the voice becoming naturally softer. Having the vocal end and adding a touch of reverb might be a better choice.
Well, one other thing. The fourth or fifth time listening through, I noticed that there’s very little space in the melody for the vocalist to take a breath - the length of the rest is too short! This makes it a little bit mechanical.
It might be nice if you doubled the vocal is some spots, but it doesn’t really need it.
Unfortunately, there’s no easy way in SynthV to do this. Just cutting and pasting the same line could mean it sounds exactly the same, which isn’t what you want. I was working on a script to jitter the durations slightly and change the phonemes to alternate phonemes, but because of the way that SynthV handles null values, that doesn’t work.
There are plenty of VSTi’s that have vocal doubler options, which would be a lot simpler.
Adding a background harmony, and mixing it in under the vocal would be the simplest thing to do if you were sticking with SynthV
I’m just so used to having suble vocal doubling added that it sounds a bit bare without it.