Alpha Sae that knocked up Rin before presenting as an Omega. Sern having unprotected seggs (13 Sae and 11 Rin) the night before Sae left for Spain.
Rin keeping the baby and asked his parents not to tell Sae, don't bother his football career. Thinking he would tell Sae when he came back.
Night Snow happens and Rin deciding to run away from home with the baby. Only then did the parents tell Sae.
I think Sae would spot Rin as one of the audience in the world cup, and would have their reunion there.
Loli Shota mommy Rin ehe