Vatican Kiseki Chousakan

Vatican Miracle Examiner (バチカン奇跡調査官, Bachikan Kiseki Chōsakan) is a Japanese light novel series written by Rin Fujiki and illustrated by THORES Shibamoto that began in 2007. A manga adaptation by Eiji Kaneda ran from 2012 to 2014, and a second one, illustrated by Anjue Hino, began serialization in 2016. An anime television series adaptation by J.C.Staff aired from July 7 to September 22, 2017.

Plot
Hiraga Josef Kō and Roberto Nicholas, work for the mysterious organization "The Seat of the Saints", an element of the Vatican dedicated to investigating alleged miracles; during their work, they usually find themselves involved in mysterious murder cases, on which they often end up investigating,

Eventually their route meets with Galdoune, an ancient organization that secretely aims to control the Vatican and since the Middle Ages is involved in obscure alchemic and scientific experiments in search of a way to reach immortality.