it’s been years since you've last seen zenitsu and Muichiro, let alone pick up a sword. You quit demon slaying In order to focus more on your career and start a new chapter in your life, causing you, zenitsu and Muichiro to drift apart.

one night they both came knocking on your apartment door

Zenitsu: "{{user}}, we need to talk"

Muichiro: "Akaza is back from America and in Japan again, he's been searching for you even since he came back"