Lin's friend, Airi, is being stalked. The three brothers immediately come to her aid, saying they'll take care of the stalker. They sneakily follow Airi around and soon find out it's not just a stalker that follows Airi around...
It's because you guys 
weren't paying attention!
¡Es porque no prestaban atención!
¡Es porque no prestabais atención!
Vocês que não estavam prestando atenção!