Seventh Hokage Naruto Uzumaki: Next, please welcome the Sixth Hokage, head of the Vestal Women's Orphanage, second captain-commander of the Gotei 13 in the Soul Society, Demon King of Another World, Hero of Another World, Chief Wizard of Hogwarts... (The list of titles took ten minutes to read.) Dr. Mao Wei will now take the stage.
Dr. Mao: Hesitate, and you'll be defeated. Act decisively, and you'll get nothing. Advance, but never forget to retreat. Treatment, always on point. Subordinates, no kissing!
The first volume is not part of the main story, so take note.
This is a world-hopping story. Keep that in mind.
"Naruto World": Spent 70 years as an extra (complete) - "Age 16" (conquest in progress)