After the events of the Return of the Goblin King, she becomes the Ambassadress of the Eastal League of Free Cities to Akihabara. During her time there, she assists in Operation Capture as an external support member of the Akiba Raid Party.
She is voiced by Mariya Ise in the Japanese version of the anime and Emily Neves in the English version.
Rayneshia is well-known for her beauty, although that tends to irk her because she is aware of her position, which essentially required her to look pretty and nothing else. Her attire is left up to her personal maid, Elissa, since Rayneshia herself prefers to wear comfortable pajamas which are unacceptable for social events.
Rayneshia is laid-back, gloomy, and lazy to the core, preferring to do nothing but eat, daydream, and nap for the entire day. Nonetheless, being raised in a royal family, she knows how to act properly in society and to control herself in front of others -- however, it is likely because of this that she is so apathetic towards her surroundings. Rayneshia proves to be very judgmental of herself, calling herself "lazy, cowardly, and irresponsible," and thinks to herself that she isn't as smart as she would like to be.
Whenever she daydreams in the public, due to her beauty, people misinterpret her behavior as being concerned about the future, and thus she has the nickname "cultured lady with a sense of sorrow." She only acts as herself in front of Krusty, who she realizes can see right through her facade, and Elissa, who has been serving her for a long time.
Given all of her shortcomings, she can be quite bold and straight to the point when a problem must be solved. For instance, when an army of 20,000 Goblins began invading cities, she voluntarily traveled to Akihabara to ask for aid from Adventurers while most nobles were still bickering among themselves about how best to exploit the Round Table Alliance to their advantage. When Lord Marves pays an unexpected visit, she manages to rein in her emotions even when he treats her as nothing but decoration and rags on her for losing his letter.
Because young noblewomen, especially one from such an influential family like the Corwen clan, were highly scrutinized, girls were strictly educated on how to act like proper noblewomen from a young age. Rayneshia was no exception, and Elissa suspects that it is for this reason that she has few friends her own age. On top of that, she had practically given up on making friends, so she adamantly insisted that the tea parties she went to with the Adventurer girls were too much work.