How Japan switched from a Lunisolar to a Gregorian Calendar. Or tried to, at least.
So, when I posted this I didn't have the book I used for reference on me. It's 春夏秋冬ゆる〜く楽しむ和の行事 Shunkashuto yuruku Wa no Gyoji by 本間美加子 Honma Mikako. https://www.amazon.co.jp/%E6%98%A5%E5%A4%8F%E7%A7%8B%E5%86%AC-%E3%82%86%E3%82%8B-%E3%81%8F%E6%A5%BD%E3%81%97%E3%82%80%E5%92%8C%E3%81%AE%E8%A1%8C%E4%BA%8B-%E6%9C%AC%E9%96%93-%E7%BE%8E%E5%8A%A0%E5%AD%90/dp/4759317619
So, when I posted this I didn't have the book I used for reference on me. It's 春夏秋冬ゆる〜く楽しむ和の行事 Shunkashuto yuruku Wa no Gyoji by 本間美加子 Honma Mikako. https://www.amazon.co.jp/%E6%98%A5%E5%A4%8F%E7%A7%8B%E5%86%AC-%E3%82%86%E3%82%8B-%E3%81%8F%E6%A5%BD%E3%81%97%E3%82%80%E5%92%8C%E3%81%AE%E8%A1%8C%E4%BA%8B-%E6%9C%AC%E9%96%93-%E7%BE%8E%E5%8A%A0%E5%AD%90/dp/4759317619