Often, as indicated in the post on Chihayafuru, competition is the arc.
When it becomes the container, the trope can take two forms (sometimes combined): a competition must be won in order for the romance to take hold, such as in You Make Me Dance. Or the competition between the leads must be resolved or accepted before the romance can take hold.
The Korean BL Mr. Heart does a great job combining both plot approaches: Sang Ha is a pacemaker to marathon runner Jin Won. Sang Hu is burdened by his family's debt to loan sharks. In order to pay them off, he ends up running with Jin Won and then winning the marathon. The series has a very amusing--and not atypical--scene where the loan sharks become invested in Sang Ha's success (see image above). Sure, they want their money. Isn't a race a great way to get it?!
Sang Ha is sure than Jin Won, who was training to win the marathon, will be angry with him, but Jin Won is a true sportsman. He wants to win; he also wants to win against a worthy opponent. Rather like Saitama, who is becoming nearly nihilistic due to the lack of challenge, Jin Won--in a somewhat less slacker-guy way--needs someone to re-inspire him.
Excellent series by the same creators of Where Your Eyes Linger.
You Make Me Dance, another Korean BL, pits the love interest directly against his debt collector, who sacrifices his plans (he thinks) to give the love interest a chance. The two fall in love. Although some reviewers worry about the power imbalance in the relationship, the power imbalance bears little weight alongside the theme--namely, artistic inspiration comes from hard work and challenge. The true villain is the "friend" who can't bear to even compete with his rival. Rather than improving himself, the "friend" tries to sabotage the protagonist to keep him from performing.
In comparison, the dancer's debt-collecting boyfriend tracks him down, pushes him to practice, protects him (without his knowledge), fixes equipment for him, admires his ability, and accompanies him to the competition.
When the judges ask the hero to name his dance, he responds in English with controlled passion, "You make me dance," a reference to his lover and a line that will break your heart--in a good way.
