Sakurada-ke no Himitsu: Otosan wa Shitappa Sentouin

is a Japanese light novel series written by Sorajuro Kashiwaba, with illustrations by Ryo-timo. The series began publication on June 10, 2008 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Gennosuke Sakurada, a 42-year-old man in a bad year. It is the main pillar of the family. Occupation is a combatant under a secret society. She is dressed in black tights day and night and works hard. Office workers are painful.

The family consists of his wife, Fumie, and his son, Gentaro, who is in the fifth grade of elementary school. It's a rare stubborn father nowadays. A new member joins the Gennosuke family. Reika, the only daughter of the Maki family, one of the world's leading wealthy people. The reason is that there is no body or lid to take care of her who was kidnapped by a secret society. There are various things if boys and girls of delicate age live under one roof. What's more, this girl, who has a cute face but is a ridiculous child, will invite Arashi to the Sakurada family !?