Kizoku No Aoi Seppun

[from Fantasy Shrine :]
Kikuchi Yo, a travel agency owner dreams of turning the “Blue Rose”, a British noble mansion into a hotel. He enthusiastically approaches Baron Gilfred, owner of the mansion, with his plans. Unbeknownst to him, he’s walking into the Baron’s trap…! A gorgeous love story between a nobleman and a business owner.
(sequel) Koushaku no Himeta Kuchizuke (continues the story of the Duke and the Prince)