VintageFromJapan > Typewriter Keys > Vintage Japanese Typewriter Key First Time in Showa Period http://www.etsy.com/listing/100980859/vintage-japanese-typewriter-key-first
This stamp is the Kanji (Chinese character) for "tachi machi" = "first time" .
It measures 2.3 cm long (long enough to be able to get a nice grip) and 5mm wide. The Chinese character itself is about 5mm wide....so please note how tiny it is. It is made of metal.