Start by Rejecting Teacher-Student Romance with Dazai

R: My senior disciple is the heir to the Cavallone family.

Dazai: Mm-hmm.

R: My junior disciple is the heir to the Vongola family.

Dazai: Mm-hmm.

R: By the same logic, you should be the heir to the Port Mafia.

Dazai: ???

Dazai again: Who said I was going to become your disciple?!

Osamu Dazai, formerly the Port Mafia's most important executive, now the number one target on the black market's wanted list.

One morning, after a failed suicide attempt left him exhausted enough to fall asleep, he awoke to a knock at the door of his damp safehouse. The visitor was a tall European man with curly sideburns. Dazai opened the door, and the man tipped his hat, decorated with an orange ribbon, and announced that he intended to become Osamu Dazai's home tutor.

Osamu Dazai: ...

Osamu Dazai expressionlessly shut the door in his face.

*Katekyo Hitman Reborn! x Bungo Stray Dogs, Reborn x Osamu Dazai. I'll be doing some wonderfully unlikely crossover pairings.

*R is Reborn, who died in the future timeline. Dazai is the Dazai who defected after Oda died.

*The map should be pretty big, and the story won't be limited to Yokohama.

*An overpowered protagonist in a sense (?). I can't imagine R ever losing.

*Also, Dazai is the shou. How could I ever ship R as the shou? (Gets on my knees.)

*The title might change.

Theme: Perhaps you really do need a good mentor. He could even be your lover.