Narita Ryohgo manga
The characters of Durarara!! have been made small and are going on a rampage in Ikebukuro! Lots of things are happening today on these streets where reality and illusion mix together!
The stage: the city of Snowfield in the western U.S., far from Fuyuki. There, a "false Holy Grail War", quite unlike the original Holy Grail War, unfolds. There were those who had been keeping an eye on the auguries of the Holy Grail in Snowfield. According to an investigation by the Mage's Association, the Holy Grail War system in Snowfield was an imitation of the one in Fuyuki. What's more, the system was incomplete, leading to the exclusion of one of the seven classes and the selection of beings as Servants who ordinarily could not be summoned. It was, verily, a strange fake. As an organ of the U.S. government executes its various plots, the Servants are summoned one after another---
From Yen Press: The serial slashings in Ikebukuro have come to an end, and Anri is steadily recovering from her injuries. But life is far from "back to normal" for Kida. Enraged at the random violence that has shattered the peace of his neighborhood, Kida and his middle school crew, the Yellow Scarves, reunite to address the rise of organized gangs in town-the Dollars, the followers of Saika, and now the Yellow Scarves. When all is said and done, who will hold the power on the streets of Ikebukuro?
From Yen Press: Ikebukuro, Tokyo—a neighborhood where twisted love prowls!! A series of street slashings in Ikebukuro begins to connect total strangers: A teenage girl with no personality of her own; a beat writer for a third-rate tabloid; a teacher suspected of harassment; an informant based in Shinjuku…and a headless rider straddling a pitch-black motorcycle!! Meanwhile, the slasher continues to terrorize the night, all in search of…“him”!?
In 1711, a group of alchemists seeking eternal life gathered on a boat to summon the "demon" that held the secret. The demon agreed to give them what they wanted—an elixir of life, the method to create more, and the secret to ending their new-found existence. The following night, alchemists began disappearing, "eaten" by one of their own. Realizing the threat being close together posed, they decided to scatter across the world. Centuries later, in Prohibition-era America, the immortals have come together once again, and the "stupid commotion" (baccano) starts.