The Ecological Perspective: "People Under the Butterbur Leaves". While the basic overview touched upon the Ainu etymology, this deep dive explores how the Koropokkuru legend is fundamentally tied to the ecology of Hokkaido and Sakhalin. The giant butterbur (*Petasites japonicus var. giganteus*) native to Hokkaido possesses stalks taller than a human adult, with leaves exceeding 1.5 meters in diameter. The custom of repurposing these massive leaves as umbrellas or roofing is common among northern hunter-gatherers, and the Ainu themselves used them daily for shelter from the rain, drying racks, and containers. The image of "little people living under the butterbur" is a direct symbolic manifestation birthed from the sheer proximity and utility of this giant plant in their daily lives.

Silent Trade as a Universal Ritual. The core of the Koropokkuru legend—"leaving goods in the dead of night and departing without ever showing their faces" (silent trade)—is not unique to the Ainu. Herodotus recorded silent trade between the Carthaginians and Libyans in his *Histories*, and identical customs have been confirmed among indigenous groups in Africa, Southeast Asia, and the Arctic. In cultural anthropology, this is defined as a "ritualized distancing to exchange goods across linguistic barriers or hostile relations." The Koropokkuru legend can be read as the narrative mythologization of this universal practice, suggesting it reflects a concrete history of trade rather than a mere fantasy of "imaginary little people."

Tsuboi and Watase's Indigenous Theory and Its Refutation. During the 1890s, Shozaburo Watase's 1886 "Pit Dwelling = Koropokkuru Theory" and Shogoro Tsuboi's subsequent anthropological hypotheses ignited a massive academic debate that engulfed the entirety of Ainu studies. The academic world was split between the mainstream camp (descending from Siebold) asserting that "Stone Age Japanese were the ancestors of the Ainu," and Tsuboi's camp arguing that "the Koropokkuru were indigenous, and the Ainu were invaders." Tsuboi's popular serialization of his theories in 1895–1896 leaked the academic debate to the general public, mass-producing the "image of the Koropokkuru" in textbooks, novels, and paintings. While post-war archaeology confirmed the "Jomon to Ainu" lineage and entirely debunked Tsuboi's theory, the debate remains a rare historical instance where an academic dispute successfully molded the national imagination.

Takuro Segawa's Paradigm Shift: "The Foreign Ainu". The innovation in Takuro Segawa's 2008 book *Who Were the Koropokkuru?* lies in rejecting the binary "indigenous or not" debate and connecting the legend to the concrete history of the Northern Kuril Ainu in the Middle Ages. He highlights the following points:

- Silent trade was actually practiced by the Northern Kuril Ainu.

- The Northern Kuril Ainu practically utilized pit dwellings into the Middle Ages.

- The use of pottery and long-distance travel to gather clay are archaeological facts of the Northern Kuril Ainu.

- The Koropokkuru legend exists everywhere *except* the Northern Kurils (as people do not mythologize themselves into "little people").

By rereading the legend not as "imagination" but as a "concrete memory of a different Ainu group," this perspective illuminates the regional differences and historical diversity *within* the Ainu, serving as an ethnographic achievement that deconstructs the monolithic image of the Ainu people.

The Departure Tale and the "Ugly Visage" Motif. The story where a curious Ainu youth grabs a Koropokkuru woman's hand, causing the tribe to flee north in shame, belongs to a universal folklore archetype: "contact with another tribe → erroneous intervention → loss of the relationship." Structurally, it is deeply related to the Greek myth of Echo, the Japanese folktale of the Crane's Return of a Favor, and the taboo of Toyotama-hime in the *Kojiki* (where looking upon the true form brings disaster). The separation caused by "seeing what must not be seen" is the mythologization of the folk ethics governing the maintenance of boundaries and respect for distance between different tribes.

Modern Children's Literature and the Ethics of Ainu Representation. Satoru Sato's post-war *Korobokkuru Tales* series (1959–) reconstructed the Koropokkuru as a unique, original fantasy world detached from Ainu folklore, becoming a multi-generational classic of Japanese children's literature. Conversely, in the 21st century, there is a growing movement demanding that mainstream works borrowing Ainu culture respect the voices and agency of the Ainu people themselves. The history of the Koropokkuru image is multi-layered, spanning academic controversies, literary creation, commercial branding (e.g., Jaga Pokkuru), and the ethics of cultural representation. Moving forward, it is necessary to move beyond consuming them merely as "cute little mascots" and to acknowledge the profound indigenous history and academic legacy that stands behind them.