Seinaru Chichi no Elf Hime

Veeta is a novice mage from a village that threatens to be consumed by the sands around if none can repair the fragile barrier protecting it from the elements. With her meager power, her only hope of saving her hometown lies at the teat of Nectia, an elven princess whose milk can imbue its consumer with mana. Elves aren't known for being welcoming to humans, so negotiating seems impossible... until she's injured into the forest and has to be nursed back to health by the very bosom she was seeking.

(Source: Irodori Comics)