Before he realized it, he was in a different world. A former Japanese office worker woke up in the body of a baby. It seems he’d been reincarnated in a different world… Although he was born into a noble family, his mother was a concubine, so his official status was that of a commoner. To such an individual, there was one person he wants to protect. She was his younger sister from the same mother. And his sister seems dead-set on never letting him go…? The life of a reincarnated and his beloved sister begins.