If someone asked who Yui Shiraishi is and if she is a sibling of Ken Shiraishi and possibly An's Aunt, well the story is quite complicated
In truth the Shiraishi Family are a well respected family as they came from a samurai family, to which it made Ken a very skilled person on Kendo along with his sister Yui, making them either 1st or 2nd place on competitions due to how they hone there skills as they were trained by there father
But Ken wanted to experience a normal life, which is why he left the household while packing his things and some money to start a new life with his sister supporting his decision despite there father warning him that if he ever leaves this house he'll never be welcomed again as a Shiraishi
With this Ken completely left and starts a new life in Shibuya, which caused him to like and pursue music and makes his name known with a help of many people that made him who he is today
Of course Ken makes sure to be with contact with Yui, who is now leading a private security company that there father has been managing until she took over due to his deteriorating health
This made Yui very aware of everything that has happened to Ken's life and as much she wanted to meet her niece the job is preventing her
That was until Ken told Yui about what Taiga did to An and her groupmates as they tried to surpass RAD WEEKEND that Nagi made before she pass away from cancer, with Yui managing to meet Taiga and Nagi a few time before when she had the chance to visit Ken without there father finding out
And it was there Yui took that personally as she immediately took a ticket back to Japan despite her duty is needed at the country she is in for a meeting, but since she is the boss of the company now just this once she'll abuse her authority and puts the meeting to another date
When she got to Vivid Street the first thing she did is find Taiga who she managed to find and then started to find a nearby wooden blunt object before Taiga notices her presence and after finding one, she charged at Taiga and started to beat the living shit of him while controlling her anger as she hits Taiga by using the swordsmanship that she honed from her father's teachings
Never in her life she ever wanted to finally beat up someone who made her niece cry and humiliated infront of this very street
Which led her here entering Weekend Garage after she kicked Taiga in the stomach which sends him crashing to the entrance of the café due to the blunt weapon she is using is destroyed and she is letting out her anger
Yui: Taiga Kotaki, for making my niece cry your fucking dead meat
Ken: Y-Yui?!
Yui: *Notices her Brother and the customers that were in the café* Ah I would like to apologize for appearing like this, I'll just take this man and we'll have a lengthy conversation elsewhere
An: W-Who are you, and why Uncle Taiga is in pain?!
Yui then takes a look at An and then sighs as she spoke
Yui: Oi Ken how didn't you even mentioned me to my Niece?!
An: Eh your Niece?!
Ken: Oh boy this is going to take awhile
About an Hour later
Due to what happened Ken had to close Weekend Garage and the customers have to leave but luckily no one complained as there order was given before all of that happened
Currently An's Mother, Yuka is currently treating Taiga's wounds in the stomach and is on the bed
And while that was happening Ken started to introduce Yui to An, surprising An as she never knew that she had a aunt until now, with An very excited to hear her father's past from her Aunt who took the spotlight after Ken explained the reason why he forgot to tell this to An due to Yui's job and there father still being alive, causing him to fear one day there father will try to get An from him
As An started to be amazed on Yui's stories about her father, Ken goes to the room where Taiga is with his wife watching Taiga with pure murder intent just like Yui's
When he enters he spoke
Ken: Told you Yui will kick your sorry ass
Taiga: I thought she could understand my reason since Nagi worked hard to organize that event before she got hospitalized
Yuka: Clearly no one in the right mind will start a singing battle when you just announced someone death to them, you should've let them grieve and if I can I'll beat up your ass if it wasn't for my husband here to stop me from doing so
Ken: Nevertheless, you must find a way to earn those kids trust back and apologize to them or else Yui will hunt you down and beat up your ass so bad you might stay there bedridden for the rest of your life
Taiga: Yeah, Yeah I'll find a way after my injuries got healed
Back to An and Yui
An: So that is very, very feared back then
Yui: Yep, your dad's Kendo skills are very high and everyone who dares to bully in the school were in were like ladies running for there lives, thou I hope your father's skill in Kendo isn't rusty since one day I wanted to fight him again
An: With that he needs to train again right?
Yui: Correct, thou do you want to learn kendo, I heard from your father your a disciplinary committee member in your school?
An: Maybe another time Aunt Yui, my group is going to have some practice tomorrow
Yui: I see. . .wait did you call me Aunt Yui
An: Yes why?
Yui: *Eyes sparkled* Can you repeat it again?!
An: E-Eh?! S-Sure. . .A-Aunt Yui
Yui proceeds to bearhug An as she squeals in joy from waiting to hear that for so long with Yui promising to be the best Aunt for An
To be continued

YOU ARE READING
The Devil's Intervention(A Project Sekai story)(Discontinued)
Fanfiction'Set before Kanade talks to Mafuyu's mom in the Immiscible Discord Event' Read the story if you want to know what will happen (Disclaimer: Project Sekai isn't mine it belongs to it's original owners(Along with the pictures and songs I'm going to use)