[There is one thing I don't understand, though.] Sister Orb wasn't finished. [If the being behind all of this doesn't want the angels to leave this Dimensional Realm through the altars, why haven't the altars been removed then?]
'I can guess the reason,' Rean said after thinking a little. 'The altars are able to send everyone out through the Chasm even though the Chasm is such a dangerous place. That shows that the power of the altars is, in fact, even higher than the Chasm itself. If I'm not wrong, the altars are the reason why space in the Azum Dimensional Realm is so sturdy. Or, it is the altars that keep the Chasm's powers in check, containing everything inside.'
Sister Orb had to admit Rean's words made sense. [Indeed. It is most likely one of these two reasons.]
