As a kid Takuma is identified as having a heart condition that needs attention. He becomes friends with his doctors being treated at the hospital. 1 afternoon Mayu overhears her daddy saying that Takumas illness is serious enough that he live beyond the age of 20. Therefore at 8-years-old he also makes a promise to marry Mayu when they turn 20, takuma isn't conscious of this himself, however. Later in life, Takuma becomes aware also he begins distancing himself from Mayu in hopes of protecting her and he will be able to help keep this claim.