Manga Like Ore ga Kokuhaku Sarete Kara, Ojou no Yousu ga Okashii.

Kageito, a butler working for the Tendo family, is the personal servant of the young lady Hoshine. One day, Kageito reports to Hoshine that a girl in his class confessed her feelings for him. Hoshine, who has harbored feelings for Kageito ever since she was a child, becomes upset… "I've been in love with Kageito for a long, long time!” And so Hoshine begins to flirt with Kageito more aggressively than ever! She nestles against him on the crowded train and begs him to sleep in the same bed with her… Meanwhile, Kageito struggles to remain her serious servant! This is a master-servant romantic comedy with a cute young lady who is trying her hardest! (Source: HJ Bunko, translated)