If you're looking for manga similar to Seigi o Aisuru Mono Gekko Kamen, you might like these titles.
Shin Baredo, a delusional "MADMAN" arrived in Tomido Citadel to find a job but got chased by the Brokers instead. He was saved by Suisui, a terrorized female MADMAN, and her family. Would his employment as a MADMEN recruiter under Link Toy Family lead him to the better life an "insane" man can have? Or would reality betray him once again?
On the very first day that Kuze Aoi transferred to Hinomiya Academy, he finds himself facing down the barrel of a gun. He is introduced to the campus and the student body by his childhood friend Miyabi and learns about the prince and princess among students, Shitara Sagiri and Hinomiya Kuon. Sagiri is a cool and beautiful while Kuon is elegant and magnificent. After school, Aoi gets lost on campus and Kuon begins shooting at him and he's barely saved by a random girl named Atarashi Sonoko. It seems that Aoi holds a secret that is critical in a feud between two old, powerful families.
Hayama Akita is also known as a Masterpieces thief: God Hand. But the art pieces he stole are copies painted by his missing mom.One day he was caught by a black market broker. A mysterious mark appears in his desparation to escape, as does his new ability, "Kannade".
A rising boss in the underworld is forced to lead a double life as a police officer and a gang boss in order to find the killer of his brother.