I really like this generalizing term for brothers and sisters.

兄弟 --きょうだい; けいてい --  siblings; brothers and sisters;

ご兄弟; 御兄弟 -- ごきょうだい --  (hon) siblings; brothers and sisters

Not every languages has such term.  In English it is "siblings', in German - 'Geschwister'.

And 2 manga series with the term 'kyoudai':

兄弟限定! by 如月弘鷹 (Kisaragi Hirotaka)

限定 --げんてい -- limit; restriction

帝国兄弟 by 舵英里 (Kaji Eiri)

帝国 --ていこく-- empire; imperial;