Akuyaku Reijou no Shitsuji-sama: Hametsu Flag wa Ore ga Tsubusasete Itadakimasu

A reincarnation story with a twist! I, Cyril, have been reborn in a new world and pledged myself to save Lady Sophia, the villainess of an otome game, from the many horrible fates that await her! I've raised her to be a proper young lady, keeping her from turning to the dark side...but apparently, she's developed feelings for me. And now the game's heroine has appeared, putting all I've accomplished at risk. Still, as her all-knowing butler, I will defy fate and ensure milady's happiness!

(Source: MANGA UP!)