Yakuza is a large Spider-like creature encountered by Samus in the power core of the BSL research station. This battle can be very difficult, because in addion to spewing fireballs, whenever it touches Samus, it picks her up, then smashes her into the ground, doing a large amount of damage. The only way to reliably avoid this is to stay in a corner as a morph ball while it is moving. It's mouth is vulnerable when it pauses to charge up its fre attack. After Samus deals enough damage to it this way, it sheds its legs and begins space jumping around the pit and dropping small slug-like projectiles. It is still vulnerable in its mouth, but because of how quickly it moves around it can be difficult to hit.
After its Core-X is defeated, Samus regains the Space Jump, allowing her to escape the pit that she fought it in, and proceed to the terminal to restore emergency power.