I would argue the major connection between both of these texts is the impossible love that lies at their core. For Ishmael and for Hatsue, just as for Tommy and Kathy, both couples eventually have to come to terms with the fact that they are doomed to not be together. For Ishmael and Hatsue, this is because of the racial and cultural divide that prevents Hatsue from ever marrying outside of her nationality, whatever her own heart might tell her. For Tommy and Kathy, their love is thwarted by their identity too, but in their case it is their identity as clones that condemn them to having their organs harvested and facing an early death. Happiness for both couples is fleeting, although they do try to convince themselves that they could enjoy a happier future together. Note, for example, how Ishmael daydreams about the kind of future he might enjoy with Hatsue:
Sometimes at night he would squeeze his eyes shut and imagine how it might be to marry her. It did not seem so farfetched to him that they might move to some other place in the world where this would be possible. He liked to think about being with Hatsue in some place like Switzerland or Italy or France. He gave his whole soul to love; he allowed himself to believe that his feelings for Hatsue had been somehow preordained. He had been meant to meet her on the beach as a child and then to pass his life with her.
Ishmael desperately tries to convince himself that he is "meant for" Hatsue, even though he realises that in order to marry Hatsue they would have to leave their families and move to a different part of the world. His dreams can be compared to when Tommy and Kathy go and visit their former headmistress, Miss Emily, to chase a rumour that they have heard that a couple who is really in love could gain a time free from having their organs harvested. However, they realise that there is nothing special about them because of the school they went to, and they hear Miss Emily tell them that they face certain death and the end of their love:
Poor creatures. What did we do to you? With all our schemes and plans?
Both couples therefore are in love, but this love is hopeless, but for different reasons. Although both texts tease the reader with the possibility that this love can achieve something of a happy ending, at the end of both stories the couples are irreversibly separated and have to accept that their love was not meant to be in the worlds in which they inhabit. This is the major link between the two texts: the theme of impossible love.