Takanashi Masaharu

Takanashi Masaharu (小鳥遊誠春), "Masa" for short, or "Anee-chan" when Aki's talking to her in front of the family in a serious setting

Aki’s family onna-oyabun, Takanashi Masaharu. Aki was adopted into the Takanashi family when he was 4 and Masa had been his big sister ever since. The two has the strongest sibling bond and trust each other with their lives, and Aki forever sad at being 1cm shorter than Masa

Aki calls her “Ane-Chan” ever since he was 4 bc being unable to speak Japanese he heard the word “aneesan” used towards older respected females. But “-chan” is used for familiarity so the young aki smashed the two words together.

Masa is fiercely protective of her little brother. Because they're from a yakuza family, both of them went to the same school, that connects the middle school to high school. She's a natural leader and goes around the school a lot to organize activities for her school life, while keeping an eye on Aki. 

When Aki entered highschool, Masa is ending her studies. Her father sent her to the US to study business in order to prep her taking over the family when the time comes. She met Shuji there, a junior of hers, at a college party, and the two striked up an unsual friendship. Probably because they're both from the same city, and that she finds Shuji's foolery absolutely hilarious.

After her studies ended she returned to Japan to fully integrate herself in the yakuza life. She starts as a low-leveled henchman, aided by Aki, who by then had trained himself to become much stronger. By understanding thoroughly how business works around her city and getting herself mingled with the people, her charisma rivaled her dad's and quickly became the local favorite.

When Masa turned 28, her father was assassinated. She then took over the seat of the head leader her father once was on. She's guided by her mother in the background to help her keep the family on track and second-handed by her brother, who will do anything she commands as the fighter of the family.