A bird has just entered my room. Please help us to see what kind of bird this is.

It should be a white-waisted bird, smaller than a sparrow. A very common little bird, there are many rice fields here, and it often feeds on grass seeds and grains. I suggest you release them, because wild birds often die of hunger strike and it is difficult to feed them. I hope it belongs to the blue sky, not the cold iron cage. If you want to keep birds, you should keep those artificially bred birds.