Medieval lexical-gloss-based commentaries on Genji monogatari are not typically treated as interpretive interventions. This essay, however, argues for a "deep reading" of glossing that takes the original source context of a glossing term as relevant to understanding the term that it glosses. Examination of the fourteenth-century Kakaishō's application of lexical glosses derived from the Tang novelette You xian ku surrounding the character of the Third Princess reveals how engagement with the source scenes for glosses from the You xian ku yields a particular and consistent reading of the Third Princess that also resonates with medieval constructs of "China" more broadly.