うちの執事は揺るがない。 1

This is a shouo romance manga set in 19th century London, in which a young lady finds herself romantically pursued by her butler, who is also her childhood best friend. As of now (February 2022) there is no English translation.

This manga has full furigana and is pretty readable. There's almost no slang or contractions, no dialects, and characters tend to speak in straightforward, polite sentences. Keigo is used, but it's nothing more advanced than what is taught in Genki II. The only hurdle with this manga is the vocabulary specific to the genre (for example 求婚者, 舞踏会, 伯爵, 社交シーズン), so be prepared to look up or guess quite a few words.

The story is your typical shoujo romance, equal parts drama, comedy, and titillation; evidently in Japan it's not considered 18+ explicit but in America it absolutely would be, so be aware that this is NSFW. The main character art is decent, but the backgrounds and secondary characters are largely ignored. Whether you'll enjoy this depends entirely upon whether you like the character of the butler, who is your typical shoujo love interest — utterly devoted but jealously possessive and domineering — so if you don't like that kind of male character, skip this manga. Otherwise, if you're a fan of steamy romance and would like to read something not super difficult, you may want to try this out.