Babban tsarin kogon dutse, wanda aka sani da Abyss, shine wuri na ƙarshe da ba'a bincika ba a duniya. Babu wanda ya san zurfin zurfin wannan rami na titan, wanda ke ɗauke da halittu masu ban al'ajabi da ban al'ajabi kuma ke cike da tsofaffin abubuwan tarihi masu ban al'ajabi waɗanda ba a san su ga mutumin yanzu ba. Drawnarnoni masu ƙarfin halin kasada sun zana ta zurfin zurfin Abyss. Da shigewar lokaci, waɗannan jaruman da suka isa gano ramin mai haɗari sai aka sansu da suna “Masu Cetowa.”
A cikin Orth, garin da ke gefen Abyss, akwai wani ƙaramin maraya mai suna Riko, wanda ke mafarkin zama babban mai bayar da fata kamar yadda mahaifiyarsa ta kasance da warware babban sirrin ramin. Wata rana, ta binciko zurfin zurfin, sai ta yi tuntuɓe kan wani ɗan ƙaramin yaro wanda ya zama mutum-mutumi…
