Ron Kamonohashi's Forbidden Deductions Kamonohashi Ron no Kindan Suiri

Ron Kamonohashi was once regarded as a genius at the top detective training academy. But after a fatal mistake, he was expelled and forbidden to become a detective. Years later, police officer Totomaru Isshiki knocks on Ron’s door seeking help on a serial murder case. He finds Ron, now a messy-haired recluse, who agrees. Together, this mismatched detective team begins solving their first mystery!

(Source: Crunchyroll)