We're the Armed Detective Agency, and We're Awesome!

Sakai Yu's childhood friend is Chuuya. Yes, that Chuuya: the kind-hearted, handsome, ridiculously strong top fighter of the Suribachi City slums, and the biggest sucker among all the leaders, the King of the Sheep. The kind-hearted, handsome King of the Sheep: What do you mean, I'm a sucker?! Sakai Yu: The Sheep definitely said it! Sheep are mean! They used to be happy eating buddies in Suribachi City, until Chuuya was betrayed by the Sheep and joined the Port Mafia. Sakai Yu lost his eating buddy. A handsome blond guy found him. "My dear, " "What a creep. You're calling a cute little boy your dear? That's seriously illegal." The Assassin King, cut off mid-speech, couldn't smile anymore: Maybe I don't need this little brother after all. Sakai Yu: If the price of running my mouth is getting sent abroad on the spot, I'll definitely watch what I say next time. His new big brother hates the world and dreams of sending it all to hell. Sakai Yu loves the world and dreams of getting his new big brother locked up. Everyone has a bright future ahead of them. The Assassin King: After being hunted by the Vindice, I finally realized this damn world should be destroyed as soon as possible. Little brothers aren't cute at all. Sakai Yu: I accidentally drove my new big brother berserk. Vongola, saviors of the suffering, please save my life! The Vongola's frozen, devoted son: I should've killed Sakai Yu ages ago. I regret it so much now. After finally escaping back to Yokohama, Sakai Yu was picked up by a squinty-eyed detective. "Come join the Armed Detective Agency!" "Do you provide food and lodging?" "And you'll get paid!" "Another delinquent organization hiring minors..." "...It doesn't count as hiring if we don't pay you." "Does that sound like something a human would say?" The squinty-eyed detective: That day, I really wanted to send him back overseas. Not long after starting his new job as an investigator for the Armed Detective Agency, Sakai Yu was targeted by an organization from another world. Time Government: I've found a promising candidate! Sakai Yu: I'm not taking a job. Seriously, no job. (Refuses frantically) Time Government: Just come and take a look. I don't believe you'll walk away empty-handed! Sakai Yu: ...You people at the Time Government sure know how to recruit Saniwa. The Sword Warriors on duty: Keep smiling. The day Chuuya joined the Port Mafia, he lost his childhood friend. Mori said that people always lose some things as they gain others. ...Then can someone tell him why that little brat he searched all over Yokohama for just suddenly came back with three employment contracts?! Sakai Yu: I lost my freedom and happiness, but gained a job and a pile of worries. Reader's guide: 1. One-on-one pairing from beginning to end, happy ending, Chuuya pairing, no secondary pairings. 2. OOC warning. If it bothers you, leave quickly. 3. A crossover with Touken Ranbu, Vongola, and other series, primarily set in Yokohama. Theme: Strength exists to protect.