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Who put that big jar of red ink on the top shelf!!
Master, it's serious!!
"taihen" can mean "serious", "great", or "emergency". The joke is that Igor seems to be just noticing that Dracula is covered in red ink, but is actually referring to the urgent letter.
Igor, you're showing your age, aren't you.
It's an urgent letter.
わかっとるっ。 こないだもきてたのだ！ 市川染五郎がドラキュラを演じているという芝居の通知だろう
I know. There was another one recently. It's probably just an invitation to watch Ichikawa Somegorou in a "Dracula" play.
"kona ida mo" means that this letter isn't the first one of it's type to arrive recently. There probably was a similar letter in the last few days.
Ichikawa Somegorou is the real stage name for a line of kabuki actors. As the current actor retires, his successor takes over the name, as in Somegorou 1, Somegorou 2, etc.
No... It's from His Excellency Prime Minister Oohira Masayoshi.
Oohiro Masayoshi really was the Prime Minister of Japan from 1978 to 1980.