Hanasakeru Seishounen

From Thomas Wang’s homepage:
A very powerful industrialist directs his daughter to pick a husband from three candidates he has chosen for her. They are to come into her life, and their uniqueness would cause her to recognize them immediately. All three of the candidates are outstanding. Well, it’s actually four…
The story evolves along the lines of a power political mystery involving a small middle eastern country.
Vol 9 contains the short story, Costume Paradise, which ran in LaLa DX.
From Baka-Updates:
Set in the modern era, the story follows the path to romance of fourteen-year-old Kajika Burnsworth, daughter of powerful industrialist Harry Burnsworth, owner of the Burnsworth international conglomerate giant. Kajika agrees to participate in a “marriage game” with her father, in which she must select her future husband out of three men that her father has supposedly preselected for her.
Despite its sh?jo-romance undertones, the story itself evolves as a power political mystery involving a small, middle eastern country called Raginei. Raginei as a country is only 1,000 years old, but became extremely wealthy within the last 50 years or so due to a change in ideals implemented by past King Machaty that allowed the international export of oil. While Kajika searches for her suitors and puzzles over the concept of love, the country is thrown into political turmoil and Kajika’s friendship with Prince Rumaty Ivan, as well as the Burnsworth relationship with Raginei, lands her right in the middle of it all.