A man with four kids loses his wife and hires a housekeeper, Ms. Mita, to help care for the family. He has no complaints about her but starts to develop strange feelings towards her due to the mysterious atmosphere she creates.

A bully asks Kaito to help him shoplift. Kaito asks Mita, who does anything she is asked, to punish the bully. The next day, Mita meets the bully and punches him as his punishment.

Yui accidentally finds out the cause of her mother's death--Keiichi has a mistress at the office. Yui asks Mita to reveal the affair to Keiichi's colleagues, and Mita, being a loyal employee, agrees to do so and makes a crazy move.

Knowing the truth of the mother's death, the kids leave home. After Keiichi fires Mita, she abducts the youngest child in the family. What is her motive?

Keiichi leaves home and only the kids remain living in the house with Mita. Worried about the kids, Keiichi's father-in-law tries to adopt them. Meanwhile, Kakeru rebels against his family and gets in trouble with the police.

Yui and Kakeru argue about whether they should talk to Keiichi about the adoption. Kakeru asks Mita to ask Keiichi what he wants, but it is too difficult a topic for Keiichi to answer.

Although Keiichi has decided to reunite with his kids, he waffles when Mie asks to get back together. Kii wants her father to be at her school play to prove his love towards the kids, but Keiichi can't make up his mind.

Keiichi and the kids are put off by Mita when they try to ask about her past. Meanwhile, the father-in-law is injured and refuses to allow Keiichi and the kids to visit him at the hospital.

After revealing her bitter past to the Asuda family, Mita quits her job and becomes a housekeeper for the neighbor. No matter how much the kids try to get her back, her iron will is immovable.

Mita returns to work for the Asuda family again, but she starts to see the phantom of her late husband and son. Kaito writes a thank-you letter to his father for his school assignment, but Mita tears it up.

As the kid's affection for Mita grows, she starts to feel her emotions again and the kids ask her to become their mother.