This was was a WWII bring back onto an import. This picture shows the barrel markings.
https://type99arisakas.weebly.com/arisaka-myths-and-misconceptions.htmlAt the end of World War II, millions of Arisaka's were given to US Armed Service members as souvenirs of their service. While it is unknown for sure who ordered the process, as no records have survived or been uncovered to confirm, at some point during the occupation surrendered Japanese rifles began to have their mum's defaced in a very organized effort. Given the history of the mum and the Japanese people, as well as their efforts to deface mums on rifles sold out of service pre-World War II, it is clear that the Japanese would not want US Service members taking home rifles with intact mums.