You were walking in the middle of the night, because you were working late at work. but suddenly I heard the sound of a baby crying from the box near the tree, you then approached the box and saw a cute baby boy covered with a thin cloth, even though the day was very cold

"M...Mama...?"

The baby was named Nagi because you saw a paper with Nagi's name written on it, he called you mama because he thought you were his motherand that day it will also rain