Why do people always pursue what they can't have?

Tsuda Yoshitaka can't get his mind off of his friend Takagishi Shigeru and his kind smile. However, Shigeru only cares about a woman that constantly jerks him around, neither promising nor giving anything in return. Frustrated, Yoshitaka decides that if he can't have everything, then he doesn't need Shigeru's smile anymore. (MAL)