Yuriko, the Tiger's Shadow

Commander ninjutsu {U}{B} ({U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand or the command zone tapped and attacking.)
Whenever a Ninja you control deals combat damage to a player, reveal the top card of your library and put that card into your hand. Each opponent loses life equal to that card's mana value.

Final Fantasy: Through the Ages

Commander Masters

Year of the Tiger 2022

Activating Yuriko's commander ninjutsu ability isn't the same as casting Yuriko as a spell. You won't have to pay the commander tax to activate that ability, and activating that ability won't increase the commander tax to pay later.

Although the ninjutsu ability has the creature enter the battlefield attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example).

Commander ninjutsu is a variant of ninjutsu that can be activated from the command zone as well as from your hand. Just as with regular ninjutsu, the Ninja enters attacking the player or planeswalker that the returned creature was attacking.

If a card in a player's library has {X} in its mana cost, X is considered to be 0.