I’ll Never Set Foot in That House Again! (Manga) Volume 3 by Milli-gram

Chelsea is finally free of her abusive birth family, and has been adopted by her maternal uncle. But before the dust can settle, a top-secret letter arrives from the neighboring Radzuel Empire. In desperate need of aid, the sender asks that Chelsea come and plant a cutting of the Spirit Tree in hopes of dispelling the miasma that has engulfed their land...

Knowing the Empire borders her adoptive father’s domain, the Sargent Margraviate, she readily accepts the request and departs, eager to meet her new relatives. Upon arrival, she’s showered with familial love and affection for the first time. Chelsea considers what she can do in return—and what better way to help than to create a seed that would clear away the miasma invading her family’s home?