The older brother, imprisoned by his sister, dies just as he escapes and is reincarnated in another world!He thought he had been freed from his demonic sister, but now she too has been reincarnated in the same world...? 

A certain boy and girl in middle school became lovers, flirted with each other, disagreed on trivial things, became more frequently irritated with each other rather than excited… and ended up breaking up on graduation.And so, the two of them, Irido Mizuto and Ayai Yume, wound up meeting each other in the most unexpected fashion.“Isn't it obvious that I'm the elder brother.” “Isn't it obvious that I'm the elder sister.”The children of the partner of their parent's remarriage was their ex-lover!?The former couple, mindful of their parent's feelings, decided on a ‘sibling rule' where the one takes conscious of the other as the opposite sex loses, but—When they encounter each other in the bathroom, commute to and from school together… along with the memories of the past and living under the same roof, just how do they disregard each other!?Russian / РусскийЭта история о парне и девушке, которые влюбились друг в друга ещё в средней школе. Тем не менее, со временем их любовь превратилась во взаимное раздражение, что привело к их расставанию после окончания школы...Но кто бы мог подумать, что судьбы Иридо Мизуто и Айя Юмэ пересекутся вновь при самых неожиданных для них обстоятельствах... Теперь они вынуждены жить под одной крышей, изображая для своих родителей сводного брата и сестру.Но оставаясь наедине и предаваясь воспоминаниям о прошлом… Смогут ли они сдержаться и не поддаться своему соблазну?!Official Twitter

An assistant to the high school counseling teacher, Rinne Akegami is an introvert who only understands what is true. As if from a revelation from God, she can point out the culprit of any crime there. What complicated matters, however, is that not even she herself understands how she does this! This is where Touya Iroha comes in — he deduces "her deductions" in order to reveal the truth, once and for all!