Based on the context and the answer, generate a question. 

Context: It was not immediate , but after a few minutes of him gazing and rhythmically wiping the window free of the fog his own warm breath caused , a familiar face , or rather , profile , walked past . Recognising him , Masuda tapped on the glass lightly with only the pads of his fingers . This however was enough to catch the person 's attention , as they looked up , gazed around confusedly for a moment before their gaze found the eyes of Masuda .

Answer:

They smile .



What may happen after the person notices who it is ?