Yeon

Yeon was a stunningly beautiful young girl with silver-white hair and eyelashes and red eyes that glowed brightly when she used her EST as Ihwa. She kept her hair tied in a ponytail, a look she had since childhood, and had a vertical scar on her face.

As for clothing, she wore a black formal suit with pants and a white lab coat-like gown whenever she was on a mission.

Yeon viewed the world with a very grim mindset, seeing nothing but blood and red even amongst the stars themselves. [1] but her overall personality is not fully known aside from Ihwa's memories of her proving to be a kind and warm person despite her gruesome job as an assassin.

However, it seems that she had a warrior mentality that she likely inherited from her father, as she wasn't afraid to show her younger sister some aspects of her job, sometimes returning home covered in blood and even asking Ihwa to avenge her if she wanted. While her exact reasons for joining the Hero Clan aren't fully known, she wanted to create a world where fragile children like Ihwa could thrive.

Yeon was born in the Age of Heroes and Villains to her father Ijincheon, a member of the Four Swordsmen, and her mother, their eldest daughter, before Ihwa arrived. It is not known exactly what her family life was like, but it is assumed that her father trained Yeon in combat and how to be a warrior during her childhood.
However, an event occurred that broke up the family, as Ijincheon decided to choose their mother over their daughters and abandoned Yeon and baby Ihwa. The reasons behind this have yet to be revealed. [3]

Yeon's life afterward is not completely unknown, but she raised Ihwa for most of her childhood as her guardian and only relative in District 17's Dust City.

Yeon, now an adult, joined the Hero Clan as a young adult and operated under the codename "Kasha". She became the youngest person to become a member of the Black Hand, the clan's personal assassination branch and special operations division that was responsible for handling the clan's "dirty work". [4]

He would also become a member of The Fingers, the leaders and strongest members of the Black Hand, as their Sixth Finger after he killed the previous one. This position was meant for those who were the strongest of the Fingers.

Yeon confronted the First Finger, Dalia Mendoza, the Punisher in a field of reeds. The Punisher engaged in a fight with her in what seemed to be an attempt to establish the hierarchy as her "senior." The two clashed with each other using their respective weapons and Quirks, but Yeon showed the Punisher how her skills earned her the title of Sixth.

Yeon was assigned to multiple missions, many of which were incredibly dangerous for long periods of time as she would disappear for weeks at a time but always make sure to return home to Ihwa. [6] During this period, others in her line of work began referring to her as The King of the Underworld. She occasionally worked with the other Fingers on various missions and at one point, warned Mendoza to be careful of "Number 7" during one of his missions.
At another point, Yeon once asked Ihwa to promise to avenge her if she ever wanted it instead of living a normal life as she alluded to the threats to her own life. Eventually, Yeon had a falling out with the clan during Operation Nightfall. Aware that Black Hand was slowly but surely tracking her, Yeon stopped by Ihwa one last time as they went to a local park to watch the stars for a night. After bringing Ihwa back to her apartment, Yeon confronted them, who had gathered many of their members and mocked them for it. She immediately began killing the assassins as she fought them off, but was severely injured by Nanzu and subdued with her Quirk.

Before they could finish her off, Yushin arrived and intervened as she fought them off and Yeon escaped in the confusion [8]. Gathering the last of her strength to return home, Ihwa found her sister as Yeon died in her arms before Yushin appeared at her door.