Manga Like Alpha Shengcun Zhinan

In order to avoid a political marriage, an alpha young master is keeping a beautiful little omega. Our young master would've never thought that the moment his omega found out that his alpha is a third year highschooler, he would not only take control of his money, but also make him study everyday! The other children of wealthy families are living a life surrounded by wine and women, yet our young master is doing five years' worth of mock college entrance exams! When our young master can't take it anymore and decids to rebel, he finds out that his lover is actually a merman, and even marked him! (Source: Kuaikan, translated) Note: Includes one extra chapter.