Vocabulary What does 6日 (むいか, muika) mean? 6日 (むいか, muika) means 6th day of the month. Quick factsReadingむいかRomajimuikaPart of speechnoun 6日むいかmuika6th day of the month1noun 6th day of the month2noun six daysAlso written: 六日Kanji in this word日day; sun