Spoilers for The Boys comic book series below
Kimiko in The Boys has one key advantage over those she fought alongside, as her origin gives her a healing factor her team members could only dream of. After being exposed to Compound V, Kimiko was turned into a weapon that was partially immune to harm, as she's able to heal from injuries like no one else on the Boys' Supe-hunting squad. As a result, she became the group's secret weapon, with powers unlike any of the others.
In The Boys #38 by Garth Ennis, Darick Robertson, Simon Bowland, and Tony Avina from Dynamite Comics, readers learn the truth of The Female's origin. It turns out, as a child, Kimiko was the daughter of the secretary of a Tokyo-based corporation that was similar to Vought-American, as they tried to make Supes with Compound V. However, after her mother brought Kimiko to work one day, the infant accidentally fell into a pot of Compound V waste. As a result, she gained powers, including incredible strength and a healing factor. After being rescued by the Boys and joining the team, she became their muscle, as she served as their secret weapon when facing superpowered threats.
The Female's Powers Were Much Stronger Than Her Teammates'
In The Boys: Selected Scripts by Garth Ennis, the writer highlighted one of the critical differences between Kimiko and the rest of the team: her healing factor powers. He went out of his way to point out how she could heal from her injuries much faster than Hughie and Mother Milk could when on Compound V. The Female's healing factor tied to her origin made her so much deadlier than the Boys, as she could not only dish out deadly blows but take them and survive where other's couldn't. Kimiko didn't need to inject herself with Compound V like her teammates, as she was always ready to fight - while also effectively immune to harm while healing quickly, making her a tough out against even the strongest Supes.
Kimiko more than proved she was the secret weapon of The Boys as she mowed through many Supes with just her bare hands, almost always coming out on top and leaving a trail of blood in her wake. Her powers were unique and never matched on the team, making her truly special among Hughie, Billy Butcher, Mother's Milk, and Frenchie - none of whom had anything close to a healing factor, making them much more vulnerable.
Ultimately, Kimiko served a valuable role in the comic book series, as she showed what Compound V could do to someone from a young age. Kimiko's tragic origin and upbringing transformed her into a silent killer with few rivals when it comes to her powers and healing factor in the world. Without her, The Boys wouldn't be nearly as effective at facing off against superpowered heroes as they were with Kimiko by their side.