The Marmoset's Paw (Patreon)

Flat-chested high school girl Abby thinks that she'll never be able to show up that busty bimbo bitch Tina... until her explorer uncle gifts her a mystical Marmoset's Paw that has the power to grant wishes. Now Abby is gifting herself a chest to envy and also gifting Tina with a definitely more...rounded physique. A story involving breast enlargement and body inflation.