Rumor had it that Oden possessed an item called a Horcrux, capable of imperceptibly influencing its holder's mind and corrupting them with Oden's influence.
That item was Oden's diary, which had ended up in Absalom's hands by sheer coincidence.
Of course, the whole Horcrux thing was just a joke. The main responsibility for that incident still lay with Kaido.
If his methods of education had been less violent, if he had not locked Yamato up with a group of samurai who worshipped Oden, there might not have been so much messy nonsense afterward.
"Have you read it?"
"I read part of it, mainly the diary. It recorded his experiences at sea, but I found it on the battlefield. Part of it was burned, and some key content is missing."
As he spoke, Absalom presented the diary with both hands.
"The Void Century, the D Clan, the Ancient Weapons... It records a great many things. Unfortunately, the section about the Great Treasure was burned away, and some of what remains is unclear."
Oran did not particularly care. Never mind that the Horcrux claim was only a joke—even if it had been Voldemort's actual Horcrux, Oran would not have cared.
When it came to soul power and Spiritual Power, there were not many people he feared. According to Bald Old Mage Ryze, in terms of Spiritual Power alone, Oran was the strongest he had ever seen.
"Abu, don't talk carelessly about this after you leave. It'll cause trouble if word gets out."
[Wano Country's Nation Founding, Joy Boy, the Pluton beneath Wano Country]
Oden's diary contained quite a bit of information. Though part of it had been burned and the contents had become fragmented, it still revealed many things.
"Rest assured, Master, I understand. But after Oden died, Kaido will probably have