月月火水木金金

Etymology
Derived from the seven days of the week, but with the weekdays, and  replaced with  and.

Originates from the.

Phrase

 * 1) "Mon-Mon-Tue-Wed-Thu-Fri-Fri" i.e. working all seven days of the week, including weekends.

Proper noun

 * 1) An Imperial Japan-era military song.