Japanese

Noun

五十日 ‎(hiragana いか, romaji ika)

1. fifty days
   • c. 1028-1107: Eiga monogatari (volume 1; page 32)

     はかなう御五十日なども過ぎもていきて、生まれ捨て三月といふに、七月廿三日に東宮にたゝせ給ぬ。

   • post 11th century: Sagoromo Monogatari (volume 2, page 182)

     まことに、かの若宮の御五十日にもなりぬれば、かゝる程も、「いかでかは」とて、内裏より、よろづに扱はせ給けり。

Noun

五十日 ‎(hiragana ごとおび, romaji gotōbi, historical hiragana ごとをび)

1. the days of the month that are multiples of 5 or 10: 5th, 10th, 15th, 20th, 25th, 30th. In Japan, financial transactions are most frequent on these days causing institutions and roads to be crowded.

References

• Matsumura, Hiroji (1964) Koten Bungaku Taikei 75: Eiga Monogatari Jō, Tōkyō: Iwanami Shoten, ISBN 4-0006-0075-3
• Mitani, Eiichi (1965) Koten Bungaku Taikei 79: Sagoromo Monogatari, Tōkyō: Iwanami Shoten, ISBN 4-0006-0079-6