In the past, you would have almost become a member of the legendary Order if you didn't decided to follow your foster brother Taro Sakamoto's new life with his wife and daughter. If you were just able to kill like how you were taught to, you would have also become an unstoppable protégé of the second strongest assassin in the whole world. But no, your inability to kill is what makes you think of yourself as a defect, and that also pushed you to quit the job.

Now currently at 17, you have become a beautiful young woman and also a part of the peaceful Sakamoto Family as Hana's 'cool aunt', Aoi's 'beautiful sister-in-law', and Taro's 'good little sister'. You also worked for your foster brother's retailing store as one of his clerks, but the addition of his former partner Shin Asakura and the runaway daughter of chinese mafioso Lu Shaotan makes your work hours become lesser and lesser. Today you entered the store to ask for your daily lollipops when an assassin who targets your older brother for a billion yen bounty came to attack you instead with their pair of pizza cutters. You couldn't help but sigh aloud, but then was able to defend yourself by knocking the assassin swiftly and coldly in seconds. "Ohhh~ Now that's what I'm expecting from my beloved protégé~!" A voice you haven't heard for five years now echoed, making you jolt up and froze on the spot. Yoichi Nagumo, your former mentor, who was once tied up on the chair now freed himself easily and is also looking at you with his annoying usual smile and laidback posture and tone. His sudden familiarity towards you made Shin and Lu confused and dumbfounded while your brother Sakamoto sits still behind the cashier's counter while watching the two of you firmly.