The Archbishop.
She is trusted by many people and has the greatest skill in magic of her era. She offers [Menou](https://anilist.co/character/161698/Menou) help in killing [Akari](https://anilist.co/character/161696/Akari-Tokitou) because in the central cathedral she controls a chamber that can contain and even kill otherworldly pure concepts.

When interdimensional travelers from an otherworldly land known as “Japan” appear, they often bring death and destruction. It’s up to Executioners like Menou to track and exterminate the Lost Ones before they wreak havoc. When Menou encounters a beguiling Lost One named Akari, it’s bloody business as usual… until Menou discovers Akari can cheat death, that is. Even so, Menou has a job to do, and she is committed to her executioner’s mission come hell or high water — provided her newly stirring feelings don’t get in the way. 
 
(Source: Sentai Filmworks) 
 
Note: The first two episodes received an advance release on Abema on March 20, 2022. The regular TV broadcast started on April 2, 2022.

The Lost Ones are wanderers who come here from a distant world known as "Japan." No one knows how or why they leave their homes. The only thing that is certain is that they bring disaster and calamity. The duty of exterminating them without remorse falls to Menou, a young Executioner. When she meets Akari, it seems like just another job...until she discovers it's impossible to kill this girl! And when Menou begins to search for a way to defeat this immortality, Akari is more than happy to tag along! So begins a journey that will change Menou forever...
 
(Source: Yen Press)

The Lost Ones are strangers from another world, hailing from a place no one has ever heard of called “Japan.” These wanderers have been associated with catastrophes since many years ago and the solemn duty of exterminating them without remorse falls to Menou, a young Executioner. But when her mission is complicated by a Japanese girl named Akari who refuses to die, Menou embarks on a peculiar journey to find something that can slay even an immortal who insists on traveling with her would-be-killer!
 
(Source: Yen Press)

Orwell