Zerozaki Hitoshiki no Ningen Kankei: Zerozaki Soushiki to no Kankei

The Zerozaki Clan is a family of demonic killers, ranked third among the Killing Names.
Zerozaki Hitoshiki, 17 years old, during Spring when he was freest and in his prime. The six Cursing Names, the counterparts to the seven Killing Names—the Tokinomiya Hospital, the Tsumiguchi Firm, the Nukumori Garden, the Shibuki Factory, the Kino Division, and the Toganagi Faction. Hitoshiki inevitably gets caught up in a battle between a messy alliance and his brother, Zerozaki Soushiki.

(Source: Kodansha, translated)