That's Japanese, and it appears to be a souvenir or memento of sorts. It says:(山林)S55.5 17
The kanji characters appear to be someone's last name, 山林 = Yamabayashi (literally 'mountain forest'). This is followed by the date written in the traditional Japanese style, where the year is marked by the reign of the emperor instead of by the western (Gregorian) calendar. The Showa era marked Emperor Hirohito's reign, from 1926-1989, and accordingly the 55th year of Showa is 1980.
So evidently someone named Yamabayashi had that $1 note in hand on May 17, 1980, and decided to make a record of that fact. It could be that they meant to take it home with them as a souvenir, or simply leave it behind as evidence of their travels.