res ▁on ▁a ▁shadow y ▁organisation ▁called ▁" The ▁Conc ern " ▁( also ▁known ▁as ▁" L ' Exp éd ience "), ▁and ▁how ▁the ▁work ings ▁of ▁this ▁organisation ▁affect ▁the ▁lives ▁of ▁the ▁novel ' s ▁multiple ▁narr ators ▁and ▁characters . ▁B anks ▁uses ▁the ▁many - world s ▁interpretation ▁of ▁quantum ▁mechan ics ▁theory ▁to ▁imagine ▁" inf init udes " ▁of ▁parallel ▁real ities , ▁between ▁which ▁The ▁Conc ern ' s ▁agents — known ▁as ▁Trans ition aries — can ▁" fl it ", ▁interven ing ▁in ▁events ▁to ▁produce ▁what ▁The ▁Conc ern ▁sees ▁as ▁benef icial ▁out comes ▁for ▁that ▁world . ▁Trans ition ing , ▁or ▁fl itting , ▁is ▁only ▁possible ▁for ▁people ▁with ▁a ▁pre dis posed ▁talent ▁for ▁such ▁movement , ▁who ▁may ▁only ▁fl it ▁after ▁ing est ing ▁a ▁myster ious ▁drug ▁called ▁" se pt us ". ▁When ▁a ▁Trans ition ary ▁fl its ▁into ▁another ▁world , ▁he ▁or ▁she ▁tempor arily ▁takes ▁control ▁of ▁the ▁body ▁of ▁an ▁existing ▁inhab it ant ▁of ▁that ▁world , ▁along ▁with ▁some ▁of ▁that ▁body ' s ▁resid ual ▁id ios ync ras ies ▁( such ▁as ▁person ality ▁dis orders ▁and ▁sexual ▁prefer ences ). ▁ ▁Main ▁characters ▁ ▁The ▁Trans ition ary ▁Refer red ▁to ▁in ▁section ▁head ings ▁as ▁" The ▁Trans ition ary ", ▁the ▁character ' s ▁name ▁is ▁Tem ud jin ▁Oh . ▁Like ▁the ▁majority ▁of ▁The ▁Conc ern ' s