Gremmy
Thoumeaux

Gremmy Thoumeaux is Sternritter V, The Visionary, and the strongest of them by his own claim and Jugram Haschwalth's private agreement. He looks like a child, sits calmly in the middle of a battlefield, and wins fights by imagining that he has won.

The Schrift is literal. Anything Gremmy pictures becomes real: a meteor overhead, a vacuum, an opponent's body freezing from the inside, a second Sternritter who existed only as long as Gremmy found him useful. Guenael Lee, the Quincy who briefly appears to be fighting Yachiru Kusajishi, turns out to be one of Gremmy's imaginings and vanishes the moment he stops thinking about it.

Kenpachi Zaraki beats him by exploiting the only constraint the ability has. Gremmy has to be able to imagine a thing accurately for it to hold together, so when he imagines a body strong enough to match Kenpachi's strength, his own body cannot support the concept and tears itself apart. He dies in pieces, still perfectly composed, having spent the entire fight testing what he could make real. It is the closest the Wandenreich arc gets to a pure thought experiment, and Kenpachi solves it by hitting it.