The White Cat That Swore Vengeance Was Just Lazing on the Dragon Kings Lap
Ongoing | Yamigo kureha,Aki | 2000 released
ch17 MC summoned to another world with her annoying friend, friend is claimed to be priestess but MC cast out to forrest, she is taken in by a kind granny, finds out she is a cherished one (aka beloved by fairies which are the source of all magic power). Goes to dragon kingdom where ML is the dragon king to learn more about the world, she disguises as a white cat. The human country who summoned her declared war on dragon kingdom to expand power.
Seijo no Maryoku wa Bannou desu