They are mission enemies in all three games, appearing after reaching a certain point in the story.
Their personality is vain, disinterested, arrogant and vindictive. It's not uncommon for warlords to issue protection missions if they somehow insult the Mosu, or payback missions issued by the equally vindictive Sadame.
The Mosu kunoichi are very fast and agile in a pinch. They tend to gather in groups and stand their distance, preferring to attack with kunai rather than be drawn into mêlée combat, if it comes to that they switch to quick and brutal attacks with claws and kicks.
Although they move slowly when patrolling, they have a tendency to stretch and lean against walls to warm up and avoid cramping, moving away from their standard patrol configurations and making them unpredictable. This also gives them the ability to see behind and above them, making sneak attacks difficult to achieve. Mosu kunoichi have a tendency to constantly talk to themselves, giving away their positions every few moments. The Mosu will sometimes be seen working alongside Ageha and Usuba during missions.
In combat, Usuba and Ageha behave similarly to the rest of the Mosu, keeping their distance from the player and attacking with a barrage of kunai. In addition, they both also have the ability to create shadow duplicates to swarm the player. It's suggested to pay attention to which one of them creates the clones, as only the originals can do this. With this in mind, it's recommended to focus on just one of the sisters during combat, as the battle ends if one of them gets her health bar depleted.
The clan originates from an unknown province and keep a nomadic lifestyle, never settling in a territory for too long. In one occasion they fought against the Asuka Clan, resulting in the death of one of their leaders: Tateha.
Way of the Ninja
Attracted by the fires of war burning in Utakata, the Mosu returned to work as mercenaries with the added intention of hunting down their leader's murderer: Goh the Crow. They are fought regularly as enemies during missions, selling their services to any warlord willing to pay.
Near the end of the first game the twin leaders tried to make a trap to ambush Goh, with Ageha disguising herself as Kinu. Many factors would derail their plans however, namely that Goh's soul had been transferred to a bear's body, Kinu's right arm was a prosthetic and Uzumushi too was vying for revenge against Kinu. During a confusing encounter Uzumushi crushed a disguised Ageha under his mace, under the impression that she was Kinu. Enraged, Usuba lashes against everyone present, later focusing on Uzumushi, though she doesn't manage to kill him then.
In a final letter to Goh, Usuba declares her quest for vengeance fruitless. Having lost both sisters in vain, she and her clan return to their homeland to bury the deceased leaders, no longer caring for Utakata or the Asuka but also warning that they will remain enemies in any future encounters.
Tales of the Ninja
The Mosu return in Tales of the Ninja as enemies in some missions.
One day many Mosu become afflicted by an unknown poison. Usuba requests the help of Kinu, a known expert in herbology, to find an antidote. Kinu delivers the antidote to Usuba, and the latter promises to repay her favor another time.
The clan is later contracted to kidnap Princess Azami to stop the possible Ichijo-Tasogare alliance, but are foiled by the Asuka. Later they are sent to assassinate Ichijo before the wedding but fail once again.
Revenge of Zen
Near the end of the game the Mosu may be the ones to capture Zaji, who basically let himself get caught to test Zen, with the intent of ransoming him. Depending on the player's actions, Zen may confront the Mosu to rescue him or may instead chase after Shu, in which case Kaede will be the one to rescue Zaji.
- The Mosu are playable characters in all games: As secret characters in Tales of the Ninja, and as skins in Way of the Ninja and Revenge of Zen.
- The clan's name 喪巣 literally translates as "Mourning Nest", hinting at the tragedy of their leaders.
- In Revenge of Zen they share the same english voice actress as Sakuya.