Ouji-sama no Iutoori♥(2009)

Ouji-sama no Iutoori♥

The student council is known as the "royal family". Wataru, the student council president, is the heir to a conglomerate and the object of every girl's adoration. Of course, Miyu is one of them. Unable to confess her feelings to him, she follows him around and he treats her like a stalker. But Wataru's grandfather takes a liking to her and she ends up joining the royal family! And what's more, a marriage agreement is forged?! Wataru is still as cold as ever to the foolish Miyu!

(Source: Shougakukan, translated)

Note: Includes 1 extra chapter.