What happens to Shinji’s pay envelope? How does he get it back?

Sjinji realizes, however, that he has lost the envelope, and that he must have dropped it on the beach. He rushes out the door without a word. A few minutes later, a girl knocks on the door and explains to Shinji's mother that she found the envelope with Shinji's name on it.

What happens at the end of Chapter 5 between Shinji and Hatsue?