As Umibozu faces Utsuro, he recalls the strongest enemy he has ever faced: someone you can find in every corner of the universe.
it's common courtesy to first knock 
on their door and introduce yourself.
.فمن الأدب أن نطرق بابه ونعرّف بأنفسنا
a etiqueta manda bater 
na porta e se apresentar.