蝦夷方言藻汐草

Yupi is the documented possessed stem of yup “elder brother” and fits ユービ, including the final vowel. Chiri also records bare third-person and extended kinship uses. Modern spelling omits the length mark and uses p; this does not establish the original vowel duration. Tamura distinguishes relational yupi from the usual address form yupo. The source only says 兄, so no address construction is inferred.