After the party has left the Calm Lands to the north-east, a boss fight against Guardian X will trigger. Upon successfully defeating the boss, the party can choose between crossing the bridge and continuing the story, or going down to the "scar's bottom", where a cave awaits.

The area is called "Cavern of the Stolen Fayth", and contains medium-to-challenging monsters, depending on how much time you've spent training your party. The cavern is pretty much straight-forward and contains several loot chests, as well as an Al Bhed Primer. In the far end of the cavern lies a save sphere, right before a boss fight.

The player will have to fight Yojimbo himself, before being able to obtain him. There are two strategies to defeat him, which work equally well.

• The first is to summon Bahamut, either normally or via Yuna's Grand Summon, and cast Mega Flare on him. Should Yojimbo not die instantly, Bahamut usually has more than enough HP to survive Yojimbo's attacks, which are pretty weak, and cast Mega Flare again. Alternatively, the player can also fill up both Yuna's and Bahamut's overdrive bar, then cast Mega Flare twice.
  
• Alternatively, Yojimbo can be defeated by casting Doom on him, either by using Kimari's Overdrive "Doom", which can be learned from the Ghosts in the area. Yojimbo will die within five rounds.

After the boss fight, the player will be able to visit the Chamber of the Fayth. Yojimbo is different than the other Aeons, and outright refuses to go with Yuna out of the kindred of his heart.
Instead, he asks Yuna for the reason of her journey, and then demands 250000 gil upfront in order to join her.

The answer you choose affects how Yojimbo acts in battle.

• "To train as a summoner."
  
• "To gain the power to destroy fiends."
  
• "To defeat the most powerful of enemies."

The detailled effects of each option are listed later, although many players gravitate towards option 3, as it's the most end-game-friendly behaviour.

After selecting an option, Yojimbo will require Yuna to make a payment for him to join him. In order to get the best possible price, first offer him half his asking price + 1 gil. So if his price is 250000 gil, offer him 125001 gil. In the second round, offer him half his asking price + 1 again. In the third and final round, you have two options:

• The economy option is to offer him 0.7 times his final offer. Round up if you're uncertain.
  
• The generous option is to offer him 3 times his final offer. This will also give you two Teleport-spheres, but has no influence on his behaviour.

Afterwards, Yojimbo is yours.

Yojimbo cannot be controlled like all other summons. Instead of being able to choose which action to perform, one can only either give him money and let him "do his thing", or dismiss him.

In order to get Yojimbo to attack, you need to pay him at least 1 gil per turn. If you pay him 0 gil, he'll get angry (more on that in later chapters) and dismiss himself. Otherwise, he'll use one of these attacks:

• Daigoro - The weakest attack, and only used if the player has bad standing or paid very little. Yojimbo will not even attack himself, but instead send his dog to attack a single enemy. You bring much dishonor to your family!
  
• Kozuka - Yojimbo will throw several throwing knives at a single enemy. They are a bit stronger than his dog.
  
• Wakizashi (Single) - Yojimbo will attack with his short-sword and strike a single enemy. A powerful attack, and often very deadly.
  
• Wakizashi (Multiple) - Yojimbo will attack with his short-sword and strike all enemies. Even more powerful than the single version.
  
• Zanmato - Yojimbo will summon a blade from the depths of hell itself and cleave all thine enemies in twain. It doesn't deal damage, it doesn't inflict status effects. It just ends them. Additional effects of Zanmato may include disbelief of the player in what just happened, or spontaneous outburts of "♥♥♥♥♥♥♥♥♥ what the ♥♥♥♥ was that!?!?!"

Which move Yojimbo will use depends on his motivation, which is calculated each turn in a series of steps I will explain in the next section. Please refer to the following table to find out how much motivation is required for each attack:


How motivation and each attack is calculated is explained in the following section!

First of all Yojinbo has a hidden stat called "Compatibility", which determines how much Yojimbo likes Yuna. His compatibility has high influence on his motivation, so keep it as high as possible. I will explain what affects compatibility below.

Yojimbo's turn is calculated in a number of steps, which are used to calculate motivation.

As soon as Yojimbo's turn begins, a calculation is made before any user input happens. This calculation determines if he attacks for free, and has a chance of (Compatibility / 1024) to succeed. Since Compatibility caps at 255, the maximum chance of getting a free attack is about 1-4.

If Yojimbo decides to do a free attack, a value F will be calculated as follows:

Since, 255 is the maximum compatibility and the system rounds down, the left part can be 63 at maximum, before a random value between 0 and 63 is added. Afterwards, an attack from his normal table is chosen, with a slight difference: If the Zanmato Level of the enemies is 1, Zanmato will be used, otherwise Wakizashi against all enemies. This means that Yojimbo might use Zanmato with about a 1/8 chance against weak enemies for free.

If a free attack was made, Yojimbo's turn ends and the next starts. Depending on the attack, compatibility may be affected.

If no free attack was made, the player will be prompted for payment. If at least 1 gil were paid, the calculation will begin.


Depending on the ammount of gil paid, the initial motivation "Motivation 1" (Motivation after step 1) will be determined.
Paying 4 Gil will yield 4 motivation. From then on, paying double the ammount will result in increments of 4 for motivation. This table should illustrate the idea:


In order to maximize gain, one should not pay more than one has to. Yojimbo doesn't care if one pays 512 gil, 600 gil, 1000 gil or 1023 gil, it'll always yield 32 motivation.


In this step, your compatibility is added to the calculation as follows:


Remember the choice you made when obtaining Yojimbo?
If you chose the first option, his motivation will change as follows:
This means that his motivation will decrease if you paid less than 25% of your total gil, and increase if you paid more, up to a 125% boost if you spent all your gil.

If you chose option 2 or 3, then this step is skipped. (Motivation 3 = Motivation 2)


Every enemy encountered in the game has a so-called Zanmato Level, rangin from 1 - 6, which affects Yojimbo's motivation. In general, the tougher a foe, the higher its Zanmato Level. How exactly will depend on your choice again:

• If you picked either option 1 or 2, your motivation will be divided by the enemies Zanmato Level:
  
  Motivation 4 = (Motivation 3 / ZanmatoLevel)
• If you picked option 3, then Motivation 3 will be multipied by 0.8 for Zanmato Levels 1-3, and by 0.4 for 4-6. This may sound like a generally better deal, but the vast majority of enemies encountered is Level 1, which means a 20% decrease of motivation. For level 6 enemies, this means only a 60% decrease, instead of a 84% decrease.

Extensive lists of Zanmato Levels of each enemy can be found in the sources at the end.


If Yojimbo's Overdrive gauge is full, it'll be depleted with the next attack and +20 motivation will be added. If not, this step is skipped.


After all these steps, a random number between 0 and 63 will be added. This is the final value of the calculation:



If Zanmato was used, then the battle is over and you're victorious.
If not, then the motivation is reset to 0 and the calculation begins anew, with the difference that the following rounds Zanmato Level is calculated like 1. This is due to the fact that basically every high level enemy will kill Yojimbo in one attack if Zanmato was not successful.

As explained before, compatibility is a hidden stat of Yojimbo, which can range from 0 to 255. When first obtaining Yojimbo, his compatibility starts at 128, which works pretty well.

Depending on several actions you take, his compatibility may increase or decrease, according to the following table:


The last entry only applies if you actively offer him 0 gil, not if he voluntarily executes a free attack. Further, letting Yojimbo die is also a bad idea. Do not use him as sacrifice unless you absolutely have to, as this will upset him.

Sadly, there is no way to measure his compatibility without savegame editors, mods or other tools. In general, if he uses Wakizashi and Zanmato often, and now and then does a free attack, you're on the right way. If he uses Daigoro often, pay him more!

My tip is to pay him 512 gil per attack in an area where enemies drop around 2000 gil per fight, such as Mt. Gagazet. This usually yields good results and increases his compatibility.

This guide was hand-written after a lot of research through the Final Fantasy wiki and other sources. Most calculations and their style were taken from this excellent guide[www.gamefaqs.com], which contains far more information than provided here. I sincerely hope that the author of the previous mentioned guide does not see this guide as copy of his. The underlying math is the same, so it's hard to express it in a different way.

Other information was taken from the wiki[finalfantasy.wikia.com], which contains more information on surrounding topics.