Parallel Worlds were other realities existing in the Evillious Chronicles universe. Due to the interventions of the god Sickle, they had a chance to have considerable variation from the reality containing the First, Second, Third and Fourth Periods.
Configuration and Laws
Parallel worlds were separate realities. They existed as branches from the main timeline, resulting from choices or events that altered the future. Parallel worlds could be studied, with Seth Twiright scientifically proving their existence while in the Second Period. Physical travel between parallel worlds was possible, whether through special "gates", the Re_birthday spell, or Black Box technology. Thanks to Sickle bringing an alternate timeline version of Allen Avadonia into the Third Period, parallel worlds had the potential to be wildly different from the Periods.
Tailor of Enbizaka World
An alternate version of the Third Period. In this timeline, Kayo Sudou did not swap bodies with Ma and gain the Prophetic Dream ability. Following her murders of the Miroku Family, Kayo learned the truth about Kai Miroku being the culprit behind the great fire and that he was a member of the Crimson Robed Masses. She alerted the Magistrate's office, causing them to move against the group, throwing the entirety of Enbizaka into a civil war, ending in the destruction of Onigashima. With the main timeline's Kayo seeing this in a prophetic dream, she sought to prevent this by instead feigning insanity at her trial, causing her to be executed as a madwoman while keeping Enbizaka safe. It is suggested that this is the setting of The Tailor of Enbizaka song.
An alternate version of the Third Period. After the destruction of the world, Allen met each of the seven demon contractors in order, eventually failing to stop Nemesis Sudou from activating Amostia and completely wiping it out. At the last moment, the alternate Allen was pulled into the Third Period by Sickle and fused with the existing Allen, allowing him to gain knowledge of the failed timeline. It is the setting of the Seven Crimes and Punishments song.
Third Period (repeat)
A repeat of the Third Period, created by Adam and Eve's Re_birthday. It existed parallel to the Third Period, and was traveled to by Adam, Eve, Irina Clockworker and Gammon Octo. It appeared to have roughly the same history as the Third Period. It is the setting of the The Karma of Evil Will Not End song.
World of Giants and Beastmen
A world containing giants and beastmen as its inhabitants. One of its continents, Silgareds, eventually fell into chaos; Banica Conchita traveled there around that time using Neo Black Box to terrorize its inhabitants as part of the Graveyard ending. It is the setting of the Banica Concerto!! song.
World of Angels and Demons
The second world traveled to by Banica Conchita and her servants. It was inhabited by both angels and demons, who eventually warred with one another, leading to the demons' defeat. The Prasino Empire existed there. It is the setting of the The Blind Girl and the Angel song.
Torture Tower World
World of Curses and Blessings
A parallel world where Rilia-Renée resided. Part of it was wrapped up in war. Like the Third Period, it had witches and artificial beings. Mothy confirmed its name in a tweet. It is the setting of The Steel Lady, Rilia-Renée song.