Spence Breast Development Clinic Itsukaichi Mei... [upd] 〈FAST × 2026〉

The exact phrase refers to a highly specialized niche in adult entertainment media rather than a physical medical institution. Specifically, it stems from a Japanese adult video (AV) concept and performance series featuring adult actress Mei Itsukaichi. The series uses a fictional, pseudoscientific medical motif centered around the "development" of the breast's sensory pathways, drawing inspiration from a real anatomical term: the Tail of Spence .

It is the portion of the upper outer quadrant of the breast that projects superolaterally into the axilla (the armpit). Spence Breast Development Clinic Itsukaichi Mei...

(Focused on the case of Itsukaichi Mei)