Being a human who can assume the substitute Shinigami form, this unique ability makes Ichigo Kurosaki the protagonist ... which was evident in arcs such as the Fullbring arc.
An example of that was how she shrunk Ichigo Kurosaki during the Lost Agent arc so he could fit on a literal Dollhouse and be able to train to develop his own Fullbring, which is a very practical ...
Riruka Dokugamine used her Fullbring power to carry a small Valley ... War episode 32 and formed an intriguing chemistry with Ichigo Kurosaki, Orihime, and others. When Orihime appeared morose ...