According to the Shinobi Syllabus for Senran Kagura: Shinovi Versus, Yagyū's parameters are as listed:
Yagyū's defense may be very high, but since her endurance is low, it's not recommended to go into combat carelessly. Take advantage of her inky aerial bullets to wear enemies down from a distance. Note that even though she has low attack, she has many multi-hitting moves that can build her Ninja Art Gauge.
Yagyū's in-game stats from level 1 to level 50. Please note the numbers listed under the level intervals (anything with a +) does not indicate how much the stat increases between the two levels but rather how much it increases for every 1 level in that range:
Lv. 2 - Lv. 10
Lv. 11 - Lv. 20
Lv. 21 - Lv. 30
Lv. 31 - Lv. 40
Lv. 41 - Lv. 50
Yagyū uses her bladed oilpaper umbrella to perform many wide-range chain attacks, building up her Ninja Art gauge fairly quickly. Her rain-based Ninja Arts have evolved to freeze her enemies. In a one-on-one situation, it's best to freeze her opponent and deal extra damage from there. Another tactic is to keep her distance, lock onto her target and charge her Breach Art holding the button. This will launch her inky aerial bullets, and if those shots successfully freeze the target, follow up with a chain attack or a Secret Ninja Art. Because Yagyū's aerial bulles have low damage, they aren't very useful against a large group of enemies. Rather than take the time to fire off ink shots against groups, go for a chain attack and lead into an Aerial Rave.
Against high-endurance enemies, hold out for a freezing hit before committing to a full-on assault. Yagyū's combo can freeze and deal some damage in its own right, so put it to good use. For larger groups, Yagyū can perform a chain attack into an Aerial Rave.
For the most part, Yagyū's Flash actics work just as well in Yang. While in Yang, however, a simple can lead into an Aerial Rave, so use it well against high-endurance enemies. In large-scale battles, it's best to mash , as it builds Yagyū's Ninja Art gauge quickly.
In Yin, Yagyū's weak attacks are enough to take out low-endurance enemies. For stronger ones, freeze them with her Breach Art, then follow up carefully for extra damage. Remember, her defense is lower in this mode, so don't get careless.