extremely annoying

Same as above

millionaire (wealth exceeding one million (10^6))

suitable for everyone and their mother

Alternative form of 万人向け (bannin-muke)

(Buddhism) eternal paradise

many mountains and rivers

pray for long live His Majesty the Emperor of Japan / one of battle cry when Banzai charge

(mathematics) geometrical

"Historical kana usage", a prescriptive method of using kana to write Japanese. Devised in the Edo period by Keichū (契沖) and taught in schools until 1946, it aims to be etymologically faithful and reflects earlier stages of the language (Heian period and earlier).