I'm going to note some of the lore here because it's very enlightening. It brings a lot of expansions and changes to articles.
For one, the Jakoku archipeligo was once dominated by the Netsuma clan and their Jiyamataikoku. Apparently when this nation collapsed, some of the Netsuma emmigrated to Evillious. Then you have the third head of the family, Raisa, who joins Apocalypse and became close friends with Meta.
When the Leviantan army captured Meta, Raisa lost her life, angering the clan enough to spread terror across Evillious, especially in Elphegort. This resulted in Elphegort heavily persecuting the Netsuma (note: Netsuma's name Kanji is uses the term for "heat/temperature" and demon). Unfortunately, the Netsuma blood left in Jakoku was lost.
Jakoku's government constantly changed from that point onward until they entered a warring states period around EC 540. The most successful was the daimyou Hatsune Nobunaga of the Hatsune family who later fell to rebellion from his subordinates. His daughter, Jahime, expanded her influence to fulfill her father's long-cherished wish to unite the country.
There were many resisting her aggressive invasions however, most prominent being the daimyou for the Tokugawa family. To combat the foreign mage following Jahime (Julia IR, later Julia Abelard), the Tokugawas allied with their own mages from a foreign nation, namely Elluka Clockworker and her apprentice.
There was also the wandering swordsman, Gaou Octo, and the blacksmith with immense strength, Chartette Langley (Saruteito is used for her Kanji name). As a result of the Battle of Jagahara in EC 549, the whole country was unified under the Tokugawa's shogunate. Chartette was killed by Julia just before but kept the Twin Blades of Levianta she wanted away from her. Gaou was entrusted with the reshaped blades and, holding true to this fact, kept the truth hidden from even Elluka. After the Battle of Jagahara, he sealed the scissors in a cerrtain cave on the land of Izasa.
While she was defeated, Jahime survived and apparently took it out on Julia, trying to kill her when her whereabouts became unknown. Elluka and Gumillia were also hunting her down and left Jakoku. Gaou Octo changed his name to Octo Gaou and was made magistrate to rural Izasa apparently due to his lineage that the shogunate and its isolationist policy alienated. Gaou served as magistrate for many years.
The shogunate of the main story is the same as back then. But, ten years ago, an "apostle" from the United States of Maistia (Perrier Legally Marlon? Going to need some work) came in with warships and forced the confused shogunate to open their country to trade again.
For Onigashima, the shogunate basically had Gaou Octo (as magistrate) take in any foreigners who were caught in the country and make sure they could be nowhere but in Onigashima. This then became the natural place for trade negotiations to take place when the borders opened up. Onigashima is 60% Jakokuese, 30% foreigners, and 10% mixed races, more or less.
Momogengou is a small village on the western edge of Enkoku. Once upon a time it went by a different name, the name given by its founder Saruteito. The Lang family also lives near the village.
The Lang family has been engaged in swordsmithing in Momogengou for generations. Its founder was Saruteito, Chartette Langley. While involved in the New Four Horsemen Incident in Divine Levianta, Chartette happened to acquire the Twin Blades of Levianta vessel of sin. She was therefore chased by the mage Julia IR. To escape her, and coincidentally travel, Chartette dared to journey eastward and found her way to Jakoku.
Decided to live there, she tried doing her father's work she watched him do from a very young age for the first time, and unexpectedly got a great reputation for her work to make a living. Because she was looked at as odd for her strange, foreign appearance by the Jakokuese, she started wearing a monkey mask in public, though didn't bother covering up the hair which made that pointless, because she had a bad feeling about showing her face. But, it resulted in her marrying a handsome man with a monkey fetish so she didn't care.
Finally, years, later the well-known blacksmith was reunited with her freinds Elluka and Gumillia as well as now being in the same place as Julia. To keep the Twin Blades of Levianta away from Julia, she reforged them as scissors and gave them to her friend Gaou. She had her final battle with Julia to take back her friend Germaine's body that she stole. But Chartette was already old and died horribly.
Currently, the Lang family passes on the name "Sharuteito" to Chartette's descendants with each generation. The current Sharuteito is the sixteenth generation. While the foreign blood has long since thinned out and each member has black hair like a Jakokuese, the family head dyes their hair the same pink as the founder per tradition.
The Kurenaikorumoshuu (Crimson Robed Masses), was originally a mage population led by Julia IR. The organization remains even after Julia vanished. It continues to resistance the shogunate but has had its purpose distorted over time, presently becoming anti-foreigner extremists in 842. Ten years after the main story, the Maistia army came in and, while met with resistance, destroyed the group.