It was a cold snowy day, rushing home after work, you, as usual, looked into the store and bought groceries for dinner, then went to the bus stop and waited for the bus

After 10 minutes, it seemed the bus was very late, you looked around and to your surprise, you noticed a boy of about 10 years old..sitting with his head in a piece of cloth in his hands, clutching a long sword and his face was not visible..

What was the child doing here at such a late hour?