Wild Ones Vol. 1,3,4,9,10 (Manga) (5 Books) by Kiyo Fujiwara 
by Kiyo Fujiwara  (Author, Illustrator)
Is she too hot to handle, even for the yakuza?

Sachie Wakamura just lost her mother, and her estranged grandfather has shown up to take care of her. The only problem is that Grandpa is the head of a yakuza gang! Sachie tries to continue living her normal life, but she can't run far since Rakuto, one of the most popular guys in school, is part of her grandfather's gang and her new protector. Soon, Sachie finds herself falling for her bodyguard. But she's the granddaughter of Rakuto's boss, so he can never show his feelings for her. Can Sachie find a way to fit into her new family and seize her chance at romance?