At the planning stage, name of 6th Ultra warrior was ‘Ultraman Star’. Then ‘Ultraman Jack’ was floated as the top candidate. However in those days hijack was a serious social problem, and ‘Jack’ could be associated with a negative image. So ‘Ultraman Jack’ was turned down. In the end ‘Ultraman Taro’ was officially adopted.
Taro used to be a common name for Japanese male especially for the first son.