Oh hell...let me try to not screw this up. Japanese is so strange to me. Any time you see Japanese writing, it is expressed in a combination of kanji, hiragana and/or katakana. The katakana is the closest thing they have to an actual alphabet, in the sense that we know it. So he basically has a big "K" painted on his stock.
You can see where the Japanese have adopted our westernized Arabic numbering too. They used Kanji "38" for Type 38 on the receiver but also our numbers for serializing the gun.