Is Yojimbo the final boss of FF10??

I've recently fallen into FF10 and I'm playing it now.. haha
I just barely managed to beat the Seymour fusion form, which had around 100,000 HP.. T_T
But after doing some searching...??
This guy called Yojimbo..?? has 1.5 million HP??;;
Not 150,000, but 1.5 million..!!
And I heard that you have to defeat this guy 5 times in a row??
Without even having time to re-equip your gear or save your progress between fights.. wow
Are there any boss monsters stronger than him.. hmm