Ryoku belongs to the Sisters, plant-based beings forged when the First Person, Riri, fractured to rescue Wakaba. As the collective’s designated observer, her domain is Sight—a sense granting literacy, enabling her to document their explorations within the Daidai. This role positions her as the group’s analytical core, her writings preserving their insights while her gaze dissects the world’s mysteries.

Driven by quiet curiosity, she navigates existence with a distant, introspective air, often seeming mentally adrift. Her sailor uniform and glasses frame an expression of perpetual distraction, as if her mind perpetually lingers among unseen threads of thought. Though her name echoes "strength," it remains an ironic footnote to her intellectual focus.

Her story concludes as all Sisters’ do: her vitality spent, she dissolves into swirling foliage. In death, her Sight, glasses, and skirt merge with Rin through assimilation, passing her legacy into another’s form. This cyclical transfer underscores the Sisters’ shared existence—fragments of Riri’s essence, bound by fragmented senses and transient lives.

Her origins mirror the collective’s; no past precedes her emergence from Riri’s division. Beyond core narratives, her presence extends solely within these defined parameters, her role confined to chronicles and the quiet dissolution that follows.