One Piece has been building to the Wano Country arc for quite a while, and the entire time fans have been privy to many rumors and hearsay as to the Lord Kozuki Oden which Kin'emon and the others are fighting so hard for. Through these powerful warriors we've learned that Oden was a respected leader of Wano 20 years ago, but we actually haven't seen much of Oden himself. This changed with the latest couple of chapters of the series that have provided a major flashback that revealed a much different Oden than expected.
But while his personality doesn't seem to be fitting for the former respected Shogun of Wano, Chapter 961 provides a great argument as to why he got so much favor as he defeats the giant boar mountain god with ease.
After some bandits kidnap one of this giant boar's children, the mountain god descended into Wano and began to eat away at the country. A young Kin'emon tries to defeat the mountain god when its piglet somehow ends up in his grasp, but he does zero damage to the giant boar. When Kin'emon fails, Oden instead hoists the young boar up high in order to draw the god's attention.
This accomplishes two things. First, it makes the people of Wano think Oden was causing more trouble by purposefully bringing the god down to attack them. Second, it gives a showcase of the kind of strength Oden has at his disposal. Poising himself to attack, Oden uses his "Oden Two-Sword Style Paradise Waterfall" and cuts the giant boar cleanly in half.
Although this incident resulted in no casualties, Oden was already disowned by his father and forced to venture out on his own at 18 years old. But with this, the young Kin'emon decided to follow him and this major event is essentially what began Oden's respectful legacy that we learn about 20 years or so later.
Eiichiro Oda's One Piece first began serialization in Shueisha's Weekly Shonen Jump in 1997. It has since been collected into over 80 volumes, and has been a critical and commercial success worldwide with many of the volumes breaking printing records in Japan. The manga has even set a Guinness World Record for the most copies published for the same comic book by a single author, and is the best-selling manga series worldwide with over 430 million copies sold. The series still ranked number one in manga sales in 2018, which surprised fans of major new entries.