A high school student who has failed to enter his/her intended college may have, depending on familial, financial, and other circumstances, the option of becoming a rōnin (浪人). As books and movies and comics have taught us, the original meaning of rōnin is masterless samurai. (See Frank Miller's Rōnin for his groundbreaking example of Dystopian ficiton.) The definition used in my students' lives is a graduate from high school who spends the following year in preparation for a second crack at entrance exams. These rōnin may study independently at home or, if the family can afford it, at a cram school most probably specializing in entrance exams.
And here, someone posted a short documentary about the 47 Rōnin legend:
And someone else posted about the historical site: