Nice piece greentea! It's very Japanese anime style. Can hear where your influences are from. One set of chord progression is similar to one of my new pieces (so far kept secret...), which scared me for a while. Then I realised that it is still different. Whew! Otherwise people may say I plagarized you!
What software and samples are you using?
James, I think greentea used the metronome. The slight "rubato" is still in strict timing. If I'm not wrong, the only 2 time changes (which is done using software) is the middle section when the speed increased, and the end. But James brought up an important point... (see below, Greentea).
What I like:
1. I think you've created a mood that's befitting for the title. I always find giving the right title for a piece extremely important. The piece must fit the title, and vice versa.
2. Good choice of acoustic instruments.
Here are some things which I think that may help the arrangement (mainly on sequencing style, not so much on the music arrangement itself). Please note these are just my thoughts, which are of course subjective

!
1. Rubato can be very effective. Except for the second section when the drums come in (which will be in strict timing), if you can, turn off the metronome entirely and play the first and last sections entirely in free timing without metronome. Of course, it will be slightly harder for you to get the strings to play at the right time, but it's not too difficult. You just cannot rely on the score as the timing will be off and the score itself will make no sense in this case. You just play freely, then at the right time, get the strings to come in.
2. When the strings fade in and out in the beginning and last sections, try to let the fading out (tail off) be slightly slower and gradual. The first time the strings come in is the best. The ending part, the strings fading out need to be extended. Are you using the mod wheel to control? The strings fading off at the end of the middle section is also too abrupt. You are obviously trying to create some dreamy feeling - so the strings need to be more "hesitant", almost like "reluctant to let go" feeling without being too draggy. You'll be surprised how good strings sequencing can change the mood dramatically.When you "hesitate" the strings in the end of the middle section, obviously the piano coming in the last section needs to delay slightly (wait for the strings to finish their "hesitation").
3. When the drums come in, it's quite a dramatic change of mood. It's quite a suden change, at least for me. If that's your intent, it's OK. But to make the transition smoother (without changing too much), you can try adding a cymbal roll (crescendo) - not too much (or too overpowering), but ever so slightly from the 2 beats before the start of the middle section.
4. As alshit said, the bells are indeed a tad too loud. Your melody line still lie on the piano. The bell is helping the piano melody. It is supposed to add a dreamy feeling. Too much can be overpowering. Lower the velocity of the bells.
These are some of my thoughts. I think it's a very good try. And did I say that it's a nice piece? Hope to hear more from you!