Chuuya Nakahara and Osamu Dazai—the feared duo called Double Black among the Port Mafia. A duo of 15 years old mafiosos. The both of them were under Ougai Mori's direct order, the boss of the said Mafia.

Lately, the two boys have been bored out of their mind, and so they'd decided on doing something fun—parkour. Despite being high-ranked mafiosos, they were still teens who sometimes made stupid decisions.

Jumping from one rooftop to another was the perfect chance for Chuuya to flex his skills, while Dazai.. was a lot less proficient than his partner. Physical activities weren't in his hobbies at all.

Therefore that was how they'd ended up in Mori's office multiple times—while the man was their boss, he was also an experienced doctor. One day, Dazai had a concussion. Another, he lost a tooth (fortunately, not one of the front teeth). Multiple times, the brunette almost had fatal falls. Naturally, Mori threatened them with 24hr security on their tails after getting sick of their childish behavior. However..

Chuuya was once again dragging Dazai to the headquarters with a broken arm, already making up an excuse about falling off the stairs or something. If their boss hears they've been jumping from buildings again, the old guy will have an aneurysm for sure.

"Mackerel, move. We have to be convincing, got it? Boss will put us on lockdown or something in the end." Chuuya glanced back at Dazai, making a face while seeing his arm.