666 (六百六十六 ) is a specific number that is most prominent and an important aspect in the Mairimashita! Iruma-kun's Demon World Universe. This includes either more than or less than six-hundred sixty-six as long as the number 6 is present.
In superstitions, the number 666 is often affiliated with devils or demons, as well as signifies evil. It is commonly interpreted as a number to invoke Satan.
The association of 666 with evil originates from a passage in the Book of Revelations in the New Testament of the Bible. As it reads in the King James Version (13:18): Here is wisdom. Let him that hath understanding count the number of the beast: for it is the number of a man; and his number is Six hundred threescore and six.
The idea of the “number of a man” or “beast” may refer to the practice of gematria in Jewish numerology, where every letter of the Hebrew alphabet corresponds to a number (e.g., aleph=1, bet=2, etc.), and words and names correspond to the sums of these numbers, which is then interconnects with the series' Demon Ranking System.
- It serves as Lord Sullivan's finger pose when he took a picture with Iruma Suzuki's Entrance Ceremony.
- Babylus Demon School has a total of 666 students enrolled.
- The formal entrance ceremony for the Babylus Demon School starts at 6:06am. (It is likely that it is 6 seconds in total, making it 6:06:06 am).
- Babel Tower has a total of 666 floors.
- Kuromu's Akudol concert had garnered 666 views on Makuboru Dome.
- The Royal One's chair of which the Demon King stood upon has 666 number inscribed on it.
- Azazel Ameri survived her Harvest Festival in 6666 minutes; of which Harvest Festival spans as the time limit.
- 6th of June (6/6) serves as the Day of the Devil.