Midokawa Nako is a transmigrant.
In her previous life as a modern-day human, she was a beautiful woman in her thirties, a kindergarten teacher who didn't believe in marriage and had been labeled infertile. She transmigrated because of a car accident.
First, she transmigrated to a world with a useless Demon King and a Demon Slayer Corps, where she became a nanny for young children... Then an accident turned her into a demon, one whose fixation was children. She died because she would rather step into the sunlight herself than kill a child.
Her mind is an overgrown field of weeds.
Just when she thinks this world is an ordinary one set in an old-fashioned era, with a relatively peaceful life, she's told it's the Demon Slayer world. As a beautiful woman in her thirties who likes watching anime, though she's not actually old, she is devastated.
Then she transmigrates again.
This time, she becomes a child born and raised in Yokohama, Japan.
Just after growing up and finding work as an orphanage teacher, Yokohama is blown up. The children at the orphanage are gone, but she survives.
That's because she awakened an ability, or perhaps a Blood Demon Art?
[Cradle]
Her ability goes out of control. While she's mentally unstable, she adopts two sons: a certain Dazai Osamu and a certain Nakahara Chuuya.
Midokawa Nako's memories from her previous two lives have grown almost completely hazy after her death in the sunlight. She only vaguely remembers having had many children and cared for many more... Her children are all good kids. Even if one likes trying to kill himself and is always wallowing in gloom, he's still a good kid. Even if one drinks, races cars, and sometimes swears, he's still a good kid. Even if one is too stubborn to take his medicine, he's still a well-behaved good kid who'll do it for his little sister. Even if one has no sense of direction, is willful, eats sweets all the time, and refuses to see the dentist, he's still a good kid.