April is called “uzuki’ in Japanese.  It is mostly well-known that it was named such because it is the month when flowers of deutzia is usually in full bloom.  There are also other stories that the sound of “u” reflects the Chinese characters of 「初」=”new” or 「産」=”be born” indicating this is the beginning of a year. (In Japan, a school year and a fiscal year start in April.)  It may have been originated from the fourth animal of the twelve Chinese zodiac, rabbit (「卯」 is for rabbit.) or a letter for planting 「植」because people used to start seeding around this time of the year.  All the other months as well that nobody knows how and why exactly Japanese named each month as such.  Still, the custom of calling each month in old-fashion way in Japan is very interesting.