Four Chinese characters - Shao Sheng Yuan Bao / Blank. 22mm, 2.04 grams. 

Very unusual small imitation of a Chinese Song dynasty coin, reportedly unearther in Japan. Have a simplified "Shao" made with two strokes, and a corrupt "Bao" in Japanese style. Certainly not an official Chinese coin or a bita-sen, but probably a local imitation of some sorts. Interesting coin.