Yamashita Motor Tricycle Business, Osaka, 1928-29
山下自動三輪車商會
Yamashita Motor made a three wheeled utililty vehicle called the Crystal Paramount (ク リ ス タ ル パ ラ マ ン ト) which used a Blackbourne engine sourced from the UK. Blackbourne sold engines to many manufacturers (principally in the UK and continental Europe) in the 1920's and into the 1930's until they ceased trading in 1937. By coincidence, 1937 happened to also be the year that the Japanese military government increased import duties into Japan to freeze out foreign imports, and which saw rates on motorcycles increase from Y74 to Y560 (a 7.5 times increase).
While the name is similar to that of Yamashita Works in Nagoya who made the Pearl Z (パールＺ) motorcycle post-war, I do not think they are related, and nothing else is known about them at this time.