Sakura Lanterns, with Japanese kanji characters.

Sakura (櫻花) means cherry tree in Japan, and this style of lantern is associated with the annual cherry blossom festival (hanami, 花見, lit. "flower viewing"). Hanami at night is called yozakura (夜桜, literally night sakura). In many places such as Ueno Park, these temporary paper lanterns are hung for the purpose of yozakura. [parts from Wikipedia]