At first glance, the Yojimbo might seem as a superior version of the Yabusame, but in reality, it plays more like a highly improved, mercenary version of the Cavalry Archer. The Yabusame itself is more comparable to a Culverin, as it has a very high bonus versus artillery combined with a good range and strong ranged resistance (50% to be precise).
On the other hand, the Yojimbo is meant to be a shock unit, quickly destroying enemy cavalry and artillery with arrow volleys, and when enemy light cavalry or infantry arrive in the battlefield, going for the kill in melee combat, where they particular excel, as they have great melee armor, combined with a strong attack, but most important of all, area damage.
Not unlike Cuirassiers or other cavalry in Trample Mode, this makes them excellent against masses of weak units, such as Strelets or Macehualtins.
All in all, Yojimbos are spectacular mercenaries, but by no means should they replace Yabusames, as they are much more expensive, and not as cost effective against Artillery, while larger masses of Light Cavalry may wreak havoc on Yojimbo.
In the Japanese campaign, they are featured in the first scenario as woodcutters who were going to be executed for rebelling. When they are freed, they will make a remark about regaining their honor and join your forces.
は [Ha.] ("Yes."; a variant of hai (はい "Yes") pronounced with a short, strong breath; old-fashioned, typically said by fictional archaic characters, especially of the feudal ages, in response to the instructions or remarks of their superior person, with an attitude of respect toward that person)
ご命令を [Gomeirei o.] ("Your instructions?")
御意(に) [Gyoi (ni).] ("At your will.")
はい! [Hai!] ("Yes!")
いざ [Iza.] ("Now.")
直ちに [Tadachi ni.] ("Immediately.")
仰せの通り(に) [Ōse no tōri (ni).] (Literally "As you say."; it means "In accordance with your will.")
The Yojimbo is the only cavalry archer that have area of effect melee attack.
The Yojimbo are classified as gunpowder units, despite obviously using arrows. While they're normally not affected by this classification, it does prevent them from benefiting from any archer-related native upgrades, such as the Carib bonus against Villagers.
The Yojimbo bears physical resemblance to the fictional character Sanjuro from a 1961 Jidaigeki film with the same name.