iz ut ani ▁( mis under standing ▁her ▁real ▁intent ions ▁towards ▁Mas ato ). ▁In ▁chapter ▁ 1 8 , ▁it ▁turns ▁out ▁" M aa - k un " ▁is ▁actually ▁Ka oru . ▁She ▁was ▁' M as ato ▁Ka oru ' ▁until ▁her ▁mother ▁rem ar ried ▁and ▁changed ▁her ▁name ▁from ▁' M as ato ' ▁to ▁' O oz ura '. ▁She ▁appeared ▁short ▁with ▁Mas ato ▁in ▁K aw ats u ' s ▁other ▁m anga ▁Ko ib ana ▁On sen . ▁▁▁▁ ▁Mar iko , ▁also ▁known ▁as ▁" Miss ▁M iz ut ani " ▁( 水 谷 先 生 ▁M iz ut ani - s ense i ), ▁is ▁Mas ato , ▁Y uki , ▁H ide ki , ▁and ▁Ka oru ' s ▁hom ero om ▁teacher . ▁She ▁becomes ▁susp icious ▁when ▁she ▁disco vers ▁that ▁Y uki ▁and ▁Mas ato ▁have ▁the ▁same ▁home ▁address ▁and ▁lives ▁together . ▁She ' s ▁quick ▁to ▁take ▁advantage ▁of ▁their ▁situation ▁in ▁order ▁to ▁keep ▁herself ▁from ▁being ▁fired ▁and ▁so ▁she ▁can ▁pay ▁her ▁over due ▁lo ans , ▁saying ▁she ▁doesn ' t ▁have ▁to ▁pay ▁rent ▁while ▁living ▁with ▁them . ▁M iz ut ani ▁is ▁a ▁r ude , ▁fre elo ading , ▁alco hol ic . ▁Ext rem ely ▁ir respons ible , ▁she ▁unw itting ly ▁allows ▁Y uki ▁drink ▁with ▁her ▁and ▁sp ends ▁all ▁of ▁her ▁w ages ▁on ▁expensive ▁goods ▁instead ▁of ▁pay ing