One Piece: I Obtained the Calm-Calm Fruit

"Mr. Yi Fan, you've transmigrated to the world of One Piece. Have you eaten a Devil Fruit?"

"Yes, the Calm-Calm Fruit."

"You joined the Marines, so you must have learned some impressive martial arts, right?"

"Yes, I learned Iron Body."

"Your Devil Fruit isn't much, and your martial arts are weak. What about Haki?"

"Yes, I've awakened Observation Haki."

"...Then how did you make it this far?"