Himekawa is a guilt-stricken by her failure to protect the citizens as they boarded the Tokyo megafloat.  When a mysterious radio signal is picked up by Atraxia, she leaps at the change to perhaps finally save a civilian.  But when Amaterasu arrives at the source of the signal, they find an enemy from another world, and one deeply connected to Himekawa's past.
we detected a weak radio signal.
detectamos débiles ondas de radio.
nous avons capté un faible signal.
detectamos um sinal de 
rádio de baixa frequência.