The Watanabe family was originally a descendant of Moritsuna WATANABE (1542 - 1620), whose imyo (another name) was 'Hanzo of Spear' and was a retainer of Ieyasu TOKUGAWA, and there were many anecdotes such as that the family was also interested in teppo (gun) and aomatsuba (blue pine needle) was used for starting a fire to cast it or that when taking nengu (land tax) from chigyo-chi (territory) they were counted with aomatsuba inserted in the bales, which is why they were called 'WATANABE of aomatsuba.'
渡辺家はもともと徳川家康の家来で「槍の半蔵」の異名を取った渡辺守綱（天文(元号)11年(1542年)-元和(日本)6年(1620年)）の末裔であるが、鉄砲にも興味を持ち、その鋳造に用いる火を起こすのに青松葉を使ったとか、知行地から年貢を受け取るとき、青松葉を俵に挿して数えた、などという逸話が多いことから「青松葉の渡辺」といわれていたらしい。