It looks like a neutral, generally the neutral in a switch is not connected to anything, but it will need testing first. The bottom red looks like the live feed. It will need testing with a meter, as it could go bang if you short it out
tiantianisfox, It is highly probable that the black and blue wires are neutral. It would be ideal if you could test them, but I would guess that you do not have the knowledge or equipment to test them. (I base this assumption on the fact that if you knew how to do it, you would not be asking on here.)
Without testing, all anyone can do is guess (Which is why I said it is highly probable the black and blue are neutral)
I would also offer the following advice. Mark each wire with a permanent marker, then take a couple more pictures with the wires still connected, so you can see the marks, this way if it does not work, you can use the new pictures to see where to put the wires back. Also measure the depth of the current back box and check what size back box your smart switch will require, often you have to change them.
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