From MangaHelpers:

This manga is based on the cell-phone rpg of the same name. Two children, Kiriru and Ignato, are born to a life of fighting. Their mother hopes that they will not end up having to fight alone. As a teenager, Kiriru does not like his assigned destiny, but he must fight monsters or many other people will die. Will he accept his fate, and will he ever find a partner? [tethysdust]

"Minimum" or "minor miracle"? special hereditary powers discovered only in an extremely limited number of humans. Those who possess such powers are known as "Minimum Holders."

Partners Nice (Ryota Ohsaka) and Murasaki (Wataru Hatano) form a detective agency called "Hamatora" in Yokohama in 2014 ? but their "office" is a table at Cafe Nowhere where they and their friends wait for clients. An old acquaintance of theirs, a cop named Art (Hiroshi Kamiya), hires them for a serial murder case he is investigating, and they discover that the murder victims are all "Minimum Holders." As Minimum Holders themselves, Nice and Murasaki are drawn into this case, whether they like it or not.