the sixth day of the month / six days

the fourth day of the month / four days

two days, a two-day period / the second day after some set point in time / the second day of the month

all day

五日 (itsuka, go-nichi, “fifth (5th) day”) / 十日 (tōka, jū-nichi, “tenth (10th) day”) / 十五日 (jūgo-nichi, “fifteenth (15th) day”) / 二十日 (hatsuka, nijū-nichi, “twentieth (20th) day”)

fifty days / Short for 五十日の祝 (ika no iwai): a Heian-period celebration on the 50th day after a child's birth / Short for 五十日の餅 (ika no mochii): mochi fed to the child during ika no iwai

the twentieth day of the month / twenty days

nineteenth day of the month

seventeenth day of the month

twelfth day of the month