Suterare Shiro Mahoutsukai no Koucha Seikatsu

Overview

In a quest to subdue a golden dragon, a white mage named Amalia is double-crossed by her party, leaving her for dead with her injuries. However, the dragon takes pity on her helpless situation and restores Amalia's health in exchange for a favor: observing human life. The dragon then takes the form of a child, using "Yuugo" as an alias. As Amalia accepts Yuugo's request, she soon realizes that ten years have since passed. Mixed with shock and confusion, Amalia tries to start a new life with Yuugo as a foster son, doing her best to fulfill her new objective. Soon enough, Yuugo begins to show interest in the culture of tea, and as someone adept in brewing them, Amalia's tea-laden life will now begin!

Source: AniList