Mayuzumi Yukie

Yukie is the eldest daughter of the Sword Saint Mayuzumi Taisei. She trained constantly in martial arts from a young age, having very little time for anything other than her domestic hobbies. Due to the time she spent training and the level of power and skill it gave her, she found herself socially isolated from her peers. Seeing this, her father made her a carved wooden horse, which she named Matsukaze. Yukie would later develop ventriloquism skills to talk to and through the horse, and considered Matsukaze to be her first friend.

A few months before her first year of high school (a few months before starting 10th grade, for us 'Muricans) her father arranged a match with Tachibana Takae, one of the four strongest martial artists in Japan. Yukie won handily, and transferred to Kawakami Academy with little fanfare. There, she meets the Kazama Family, and starts on a quest to make 100 friends.

Yukie is considered the weakest member of the Big Four, though this comes with the oft-noted caveat that this is because she's the youngest and has the least combat experience. Her excessive humility and her stated goal to make friends means that she doesn't fight very often, but she is very aware of her own strength; she often uses ambiguous syntax to make herself seem weaker and non-threatening so that her skill doesn't isolate her.

Battle vs Assassin (by Leolab)
No Battle Written

Expert's Opinion
Both combatants were equally matched, with the natural abilities of Assassin's Servant skills canceled out by Yukie's talent and techniques