Sui (the main character) who was an office lady seems to have reincarnated in another world due to an accident and came to another world, and Sui decided to live with Cain and Phil of the chemo ear race as Tsugai. One day, Cain gave off a fever that couldn't be cured even by magic, and Phil 's appearance was strange. Sui went to see Cain's appearance during work, and found out the true meaning of Tsugai there. Tsugai was supposed to be the partner of the intense estrus period. Cain and Phil became the estrus period at the same time, and even Sui due to the influence of the aphrodisiac effect peculiar to the estrus period ... )