Answer:
They all have a reading that is the same backwards.
南 NAN, minami - south
危 KI, abu(nai), aya(ui) - danger, dangerous
違 I, chiga(u), chiga(eru) - be different, alter, be mistaken
囲 I, kako(u), kako(mu) - surround, enclose, besiege
襲 SHUU, oso(u) - attack, assail, succeed to, inherit