どタイプお姉さんの誘惑が止まらないっ！ ちっちゃい頃から私のことがだいすきな年下従妹のお嫁さんになっちゃいました!?

Until death do us part... let's stay together forever, big sis! Otose Koito is a high school girl who fell into a coma after an accident while protecting her young cousin. When she wakes up, she finds herself in a world 10 years in the future!? Her cousin has grown into the adult woman she likes and is increasingly coming on to her - her sanity is at its limit with these exciting days!?