The Iwatobi Swim Club needs one more member before it can participate in relays.  Nagisa has set his sights on his classmate Rei, who is a member of the track team.  Despite Rei's refusal to join, but Nagisa appears intent on recruiting Rei into the swim club.
That's your reason?!
Das ist deine Begründung?!
¡¿Ese ese el motivo?!
¡¿Ese es el motivo?!
Pour cette raison-là ?
Per questo motivo?!
É esse o seu motivo?!
По этой причине?!