Senko
A bone-shattering is one of the most excruciatingly painful things someone can go through. Senko has a rather high tolerance for pain, but...
she thought the horrific side effects of her first use of cell grafting hurt, but this... Yeah. This is bad.
Especially since there are a lot of blood vessels in bone.
As shards and... honestly quite a lot of blood hit the floor, Senko is forced to retract what's left back into her body.
This is bad: The bones of a dead Bone Pulse User are stronger and denser than normal human bone. If he can hit hard enough to shatter them then none of Senko's defensive abilities can hold up.
And then Senko gets hit by another bone-breaking blow.
...Though the pain is worse, thats no the only difference between this pain and the previous contender for worst pain in her life: She didn't have the genes for a stress-activated dojutsu then.
Her vision blurs briefly, but then she looks up and her eyes are glowing a solid, vibrant white.
The Raizagan's properties are determined by the elemental affinity of the user. Reiko's affinity is wind, so hers fires cool beams that effortlessly pierce most things.
Senko's, despite her grafting, is naturally yang, the element of life, light, and physicality. His eye beams are bright and warm, behaving like lasers... Until they hit the target, where instead of cutting or burning, they hit like raw kinetic force.
Senko fires such beams by reflex as the dojutsu activates... And happens to be looking at the White Oni at the time.
"...Break... That..."
Baku
This isn't his first rodeo, he knows that sometimes these so-called prodigies like to get cute.
He twists at the Shuriken and uses what Kimiko might recognize as Wind Release: Great Breakthrough to blow them away.