Aoba

Aoba doesn't have a weapon that she habitually uses or likes most. Her strong suit is the art of turning anything into a weapon, from the hairpin on her head to a piece of napkin she offhandedly gets. The numerous skills she picked up from various channels have made things like restraining enemies or rapidly knocking out someone a total walk in the park for her.
Observing the way she does things, you may easily be reminded of an overly devoted ninja in movies. Truth is, she has indeed learned a thing or two from Mugenryu's traditional combat techniques, but Mugenryu's ninjutsu was succeeded by someone else, for she wasn't up to the mark... This didn't matter to her, though. So long as she's capable of utilizing the combat techniques of other factions, Aoba will always earnestly learn them, all so her useless self won't end up burdening Yoizuki. That is in spite of the fact that others already think she's more than impressive.
Yoizuki doesn't mind joining in on the entertainment activities on the train, whereas Aoba generally just observes in silence from afar. There has only been one instance when Aoba passed by Eliot and Fran, who were practicing dart-throwing, and asked softly, "May I give it a try too?"
Afterward, according to Eliot's recountal... "Save for nearly swiping the dartboard off the wall the first time, she hit bullseye consecutively the next few throws!"

Yoizuki's favorite snack is Rakugan, favorite place is somewhere quiet that overlooks the city, and favorite thing to do is to make people obey her—these are things that Aoba has deeply imprinted in her mind. But when someone asked her what she liked, she was lost for words. That had happened after a hair-raising combat mission concluded, and The Eternal's crew planned to prepare a gift or cake for Aoba according to her preference at the celebration party.
"There's nothing I like," was Aoba's eventual response. To her, "like" and "love" were both needless emotions. Even if she had them, she had long given them all to Yoizuki.
As such, the crew could only do their best to list out cake types and flavors and request Aoba to select one. They even comforted her by saying that Yoizuki couldn't make it to the celebration party this time, so Aoba could feel free to choose something she preferred, even if it were a flavor she "least hated"!
In the end, Aoba picked a pink cake embellished with cream flowers and some decorative leaves. Everyone teased grinningly, "So Aoba likes pink too, huh!"
Only Aoba knew that the cake had reminded her of a time when she shared snacks with Yoizuki as children. The snacks they had at home were always the few that Yoizuki liked, and only Yoizuki would take note of whether Aoba had eaten, as well as hand Aoba a snack with a smile. In Aoba's memory, as long as it was a snack given to her by Yoizuki, it would taste the best in the world.

The place where Aoba lives alone in the city is also home to a little dog. She had met the dog on one of the rare nights when Yoizuki gave Aoba time off. With a smile, Yoizuki tenderly told Aoba that Aoba could rest for the night, saying "You must also be tired after our long day outside, right...? Leave the rest of the negotiations to me," before gently shutting the door. Aoba had hoped she could help Yoizuki in some way, only to achieve nothing.
As she walked back to her residence, Aoba came across a filthy little dog with a missing patch of fur and scrape wounds on its legs. It was extremely fearful of humans yet cautiously and piteously whimpered at Aoba. For some unknown reason, Aoba squatted down by the roadside and spent some time to earn the dog's trust before taking it to the vet. It goes without saying that it eventually went home with her.
Yoizuki didn't like animals and detested dogs, in particular, for dogs would sniff around and bark randomly, making them a menace if not trained well. If Yoizuki were to find out Aoba had adopted a stray dog in her small apartment, Yoizuki would undoubtedly get mad and might even punish Aoba, so Aoba never told Yoizuki about the dog, feeling simultaneously guilty about having to hide something from her baby sister and reluctant to part with her new pet. With that, she lived every day in fear of ultimately getting found out by Yoizuki.
These days, whenever she returns to her apartment in the time-worn residential building, the now spotless, fluffy, and healthy dog will happily welcome Aoba at the door. "Even I deserve to have this little bit of joy, right...?" she ruminated each time she petted the dog.