Coins made from nickel and copper began to be withdrawn by the Japanese government in December 1942, replacing them for aluminum coinage. More aluminum was taken out of ten sen coins on February 5, 1943 by Royal Decree No. 60. This action lowered the weight of the coin further from 1.2 to 1 gram as the metal became difficult to obtain. An announcement by the Japanese government was eventually made in April 1943 regarding plans to replace aluminum coinage with tin. Aluminum was officially abolished for coinage by the end of the year in favor of the new alternate alloy. One of the main reasons for using tin centered around it being relatively easy to obtain from occupied territories in Southeast Asia. The decision was not made lightly, as tin was a strategic material which is unsuitable for monetary purposes as the metal is soft. Ten sen coins using this alloy were enacted on March 8, 1944 by Royal Decree No. 388. These coins are reduced in size from 22 to 19mm, the weight was increased from 1 to 2.4 grams, and a central 5mm hole was added. The design for these coins simply feature a chrysanthemum seal and paulownia on the obverse, and inscriptions on the back. Production only occurred for a few months before being discontinued due to allied air superiority and control over the seas. Ten sen notes were ultimately issued when materials could no longer be secured for coins. Unissued porcelain ten sen pieces were also made, but were mostly destroyed when World War II ended.
