is this pun from 7th days which read nana in japan and her secretary line which says 'kyou wa nanohi' ? Edit:Now i get it that was chinese zodiac isn't it
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ThursdayJanuaryWednesdayDog dayJanuaryTuesdayJanuaryKancolle Calendar IT'S NENOHI!the next in the Chinese zodiac is Rat, which is in the calendar is written as '子' and read as /ne/.Pig day