The strongest schoolgirl in the underworld descends! The Grim Reaper with a school bag on her back.Residents of the underworld call her "Death Size Cutie." Satoko Sato is a woman on the brink of disaster when she falls for a marriage scam and is caught embezzling from a yakuza front company. Satoko is on her knees at the gang's office, and in return for clearing her debts, she is offered a mission: to become the "older sister" of Lilja, an elementary school student whose true identity is unknown. And so begins the noisy daily life of these two uneven "sisters." Violent, beautiful girl gun action interwoven with guns and school bags!