To get to Yojimbo, go to the Calm Lands and head up where you have fought Defender X. There descend in the gorge just before Mt. Gagazet. You will be in the Cavern of the Stolen Fayth. Now make your way up and turn right when you can, follow the path and you will see that you can turn right into a small alley, go there and pick the chest at the end for a Megalixir. Continue your way up until you see an intersection, go right first and pick the chest at the end for a Lv. 2 Key Sphere, now follow the path up and you will see an intersection. Go up first and pick the rare Fortune Sphere in a chest there. Now go back to the intersection and go left this time. Continue on that way to find another intersection. Go left and pick up the Al Bhed Primer Vol. XXV. Continue on the path after that to meet a Save Point and Save your game, because there is a tough boss coming up.
Continue on your way up to find the first summoner that Lulu guarded. The summoner is dead of course and you will need to fight her Yojimbo !
This is a pretty easy fight, use the fact that this boss has a very low magic defense. So bring Lulu in the fight to cast your most powerful spells. Use Auron to deal physical attack on him and Yuna to heal your party. This is a pretty easy fight and it’s possible to beat him before he get his Overdrive !
Once you have defeated it, continue up to find a teleport pad on the ground. Before going up, head right and left for hidden areas with three chests. You can pick up a Flexible Arm in the left room and a MP Sphere plus two X-Potions in the right room. Once you are ready, continue your way up and I hope you have a lot of money.
You will meet Yojimbo and he will ask you money for his services. First, select the option “To defeat the most powerful enemies” so he will ask you a lower amount of Gil. Now, you can hire Yojimbo. In my case, he asked me 300,000 Gil. Ask him 150,001 Gil, so he will lower his price by 40 000 Gil, you can take that offer if you want or try to bid a lower price. If at any point of the bid you offer him triple of the price he ask, he will give you two Teleport Spheres and he will join your party. Once you have Yojimbo in your team, return to the place where you hired him and you can pick up a Strenght Sphere! Great Job, you have completed the first Sidequest !